cc/scheduler/scheduler_unittest.cc

// Copyright 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/scheduler/scheduler.h"

#include <stddef.h>

#include <string>
#include <vector>

#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/message_loop/message_loop.h"
#include "base/numerics/safe_conversions.h"
#include "base/run_loop.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "cc/test/begin_frame_args_test.h"
#include "cc/test/fake_external_begin_frame_source.h"
#include "cc/test/ordered_simple_task_runner.h"
#include "cc/test/scheduler_test_common.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

#define EXPECT_ACTION(action, client, action_index, expected_num_actions)  \
  do {                                                                     \
    EXPECT_EQ(expected_num_actions, client->num_actions_());               \
    if (action_index >= 0) {                                               \
      ASSERT_LT(action_index, client->num_actions_()) << scheduler_.get(); \
      EXPECT_STREQ(action, client->Action(action_index));                  \
    }                                                                      \
    for (int i = expected_num_actions; i < client->num_actions_(); ++i)    \
      ADD_FAILURE() << "Unexpected action: " << client->Action(i)          \
                    << " with state:\n" << client->StateForAction(i);      \
  } while (false)

#define EXPECT_NO_ACTION(client) EXPECT_ACTION("", client, -1, 0)

#define EXPECT_SINGLE_ACTION(action, client) \
  EXPECT_ACTION(action, client, 0, 1)

#define EXPECT_SCOPED(statements) \
  {                               \
    SCOPED_TRACE("");             \
    statements;                   \
  }

namespace cc {
namespace {

base::TimeDelta kSlowDuration = base::TimeDelta::FromSeconds(1);
base::TimeDelta kFastDuration = base::TimeDelta::FromMilliseconds(1);

class FakeSchedulerClient : public SchedulerClient,
                            public FakeExternalBeginFrameSource::Client {
 public:
  FakeSchedulerClient()
      : automatic_swap_ack_(true),
        scheduler_(nullptr) {
    Reset();
  }

  void Reset() {
    actions_.clear();
    states_.clear();
    will_begin_impl_frame_causes_redraw_ = false;
    will_begin_impl_frame_requests_one_begin_impl_frame_ = false;
    draw_will_happen_ = true;
    swap_will_happen_if_draw_happens_ = true;
    num_draws_ = 0;
    last_begin_main_frame_args_ = BeginFrameArgs();
  }

  void set_scheduler(TestScheduler* scheduler) { scheduler_ = scheduler; }

  bool needs_begin_frames() { return scheduler_->begin_frames_expected(); }
  int num_draws() const { return num_draws_; }
  int num_actions_() const { return static_cast<int>(actions_.size()); }
  const char* Action(int i) const { return actions_[i]; }
  std::string StateForAction(int i) const { return states_[i]->ToString(); }
  base::TimeTicks posted_begin_impl_frame_deadline() const {
    return posted_begin_impl_frame_deadline_;
  }

  int ActionIndex(const char* action) const {
    for (size_t i = 0; i < actions_.size(); i++)
      if (!strcmp(actions_[i], action))
        return base::checked_cast<int>(i);
    return -1;
  }

  bool HasAction(const char* action) const {
    return ActionIndex(action) >= 0;
  }

  void SetWillBeginImplFrameRequestsOneBeginImplFrame(bool request) {
    will_begin_impl_frame_requests_one_begin_impl_frame_ = request;
  }
  void SetWillBeginImplFrameCausesRedraw(bool causes_redraw) {
    will_begin_impl_frame_causes_redraw_ = causes_redraw;
  }
  void SetDrawWillHappen(bool draw_will_happen) {
    draw_will_happen_ = draw_will_happen;
  }
  void SetSwapWillHappenIfDrawHappens(bool swap_will_happen_if_draw_happens) {
    swap_will_happen_if_draw_happens_ = swap_will_happen_if_draw_happens;
  }
  void SetAutomaticSwapAck(bool automatic_swap_ack) {
    automatic_swap_ack_ = automatic_swap_ack;
  }
  // SchedulerClient implementation.
  void WillBeginImplFrame(const BeginFrameArgs& args) override {
    PushAction("WillBeginImplFrame");
    if (will_begin_impl_frame_requests_one_begin_impl_frame_)
      scheduler_->SetNeedsOneBeginImplFrame();
    if (will_begin_impl_frame_causes_redraw_)
      scheduler_->SetNeedsRedraw();
  }
  void DidFinishImplFrame() override {}

  void ScheduledActionSendBeginMainFrame(const BeginFrameArgs& args) override {
    PushAction("ScheduledActionSendBeginMainFrame");
    last_begin_main_frame_args_ = args;
  }

  const BeginFrameArgs& last_begin_main_frame_args() {
    return last_begin_main_frame_args_;
  }

  DrawResult ScheduledActionDrawAndSwapIfPossible() override {
    PushAction("ScheduledActionDrawAndSwapIfPossible");
    num_draws_++;
    DrawResult result =
        draw_will_happen_ ? DRAW_SUCCESS : DRAW_ABORTED_CHECKERBOARD_ANIMATIONS;
    bool swap_will_happen =
        draw_will_happen_ && swap_will_happen_if_draw_happens_;
    if (swap_will_happen) {
      scheduler_->DidSwapBuffers();

      if (automatic_swap_ack_)
        scheduler_->DidSwapBuffersComplete();
    }
    return result;
  }
  DrawResult ScheduledActionDrawAndSwapForced() override {
    PushAction("ScheduledActionDrawAndSwapForced");
    return DRAW_SUCCESS;
  }
  void ScheduledActionCommit() override {
    PushAction("ScheduledActionCommit");
    scheduler_->DidCommit();
  }
  void ScheduledActionActivateSyncTree() override {
    PushAction("ScheduledActionActivateSyncTree");
  }
  void ScheduledActionBeginOutputSurfaceCreation() override {
    PushAction("ScheduledActionBeginOutputSurfaceCreation");
  }
  void ScheduledActionPrepareTiles() override {
    PushAction("ScheduledActionPrepareTiles");
    scheduler_->WillPrepareTiles();
    scheduler_->DidPrepareTiles();
  }
  void ScheduledActionInvalidateOutputSurface() override {
    actions_.push_back("ScheduledActionInvalidateOutputSurface");
    states_.push_back(scheduler_->AsValue());
  }

  void SendBeginMainFrameNotExpectedSoon() override {
    PushAction("SendBeginMainFrameNotExpectedSoon");
  }

  base::Callback<bool(void)> ImplFrameDeadlinePending(bool state) {
    return base::Bind(&FakeSchedulerClient::ImplFrameDeadlinePendingCallback,
                      base::Unretained(this),
                      state);
  }

  void PushAction(const char* description) {
    actions_.push_back(description);
    states_.push_back(scheduler_->AsValue());
  }

  // FakeExternalBeginFrameSource::Client implementation.
  void OnAddObserver(BeginFrameObserver* obs) override {
    PushAction("AddObserver(this)");
  }
  void OnRemoveObserver(BeginFrameObserver* obs) override {
    PushAction("RemoveObserver(this)");
  }

 protected:
  bool ImplFrameDeadlinePendingCallback(bool state) {
    return scheduler_->BeginImplFrameDeadlinePending() == state;
  }

  bool will_begin_impl_frame_causes_redraw_;
  bool will_begin_impl_frame_requests_one_begin_impl_frame_;
  bool draw_will_happen_;
  bool swap_will_happen_if_draw_happens_;
  bool automatic_swap_ack_;
  int num_draws_;
  BeginFrameArgs last_begin_main_frame_args_;
  base::TimeTicks posted_begin_impl_frame_deadline_;
  std::vector<const char*> actions_;
  std::vector<std::unique_ptr<base::trace_event::ConvertableToTraceFormat>>
      states_;
  TestScheduler* scheduler_;
};

class SchedulerTest : public testing::Test {
 public:
  SchedulerTest()
      : now_src_(new base::SimpleTestTickClock()),
        task_runner_(new OrderedSimpleTaskRunner(now_src_.get(), true)),
        fake_external_begin_frame_source_(nullptr) {
    now_src_->Advance(base::TimeDelta::FromMicroseconds(10000));
    // A bunch of tests require NowTicks()
    // to be > BeginFrameArgs::DefaultInterval()
    now_src_->Advance(base::TimeDelta::FromMilliseconds(100));
    // Fail if we need to run 100 tasks in a row.
    task_runner_->SetRunTaskLimit(100);
  }

  ~SchedulerTest() override {}

 protected:
  TestScheduler* CreateScheduler() {
    BeginFrameSource* frame_source;
    unthrottled_frame_source_.reset(new BackToBackBeginFrameSource(
        base::MakeUnique<TestDelayBasedTimeSource>(now_src_.get(),
                                                   task_runner_.get())));
    fake_external_begin_frame_source_.reset(
        new FakeExternalBeginFrameSource(0.f, false));
    fake_external_begin_frame_source_->SetClient(client_.get());
    synthetic_frame_source_.reset(new DelayBasedBeginFrameSource(
        base::MakeUnique<TestDelayBasedTimeSource>(now_src_.get(),
                                                   task_runner_.get())));
    if (!scheduler_settings_.throttle_frame_production) {
      frame_source = unthrottled_frame_source_.get();
    } else if (scheduler_settings_.use_external_begin_frame_source) {
      frame_source = fake_external_begin_frame_source_.get();
    } else {
      frame_source = synthetic_frame_source_.get();
    }

    std::unique_ptr<FakeCompositorTimingHistory>
        fake_compositor_timing_history = FakeCompositorTimingHistory::Create(
            scheduler_settings_.using_synchronous_renderer_compositor);
    fake_compositor_timing_history_ = fake_compositor_timing_history.get();

    scheduler_.reset(
        new TestScheduler(now_src_.get(), client_.get(), scheduler_settings_, 0,
                          task_runner_.get(), frame_source,
                          std::move(fake_compositor_timing_history)));
    DCHECK(scheduler_);
    client_->set_scheduler(scheduler_.get());

    // Use large estimates by default to avoid latency recovery in most tests.
    fake_compositor_timing_history_->SetAllEstimatesTo(kSlowDuration);

    return scheduler_.get();
  }

  void CreateSchedulerAndInitSurface() {
    CreateScheduler();
    EXPECT_SCOPED(InitializeOutputSurfaceAndFirstCommit());
  }

  void SetUpScheduler(bool initSurface) {
    SetUpScheduler(base::WrapUnique(new FakeSchedulerClient), initSurface);
  }

  void SetUpScheduler(std::unique_ptr<FakeSchedulerClient> client,
                      bool initSurface) {
    client_ = std::move(client);
    if (initSurface)
      CreateSchedulerAndInitSurface();
    else
      CreateScheduler();
  }

  OrderedSimpleTaskRunner& task_runner() { return *task_runner_; }
  base::SimpleTestTickClock* now_src() { return now_src_.get(); }

  // As this function contains EXPECT macros, to allow debugging it should be
  // called inside EXPECT_SCOPED like so;
  //   EXPECT_SCOPED(client.InitializeOutputSurfaceAndFirstCommit(scheduler));
  void InitializeOutputSurfaceAndFirstCommit() {
    TRACE_EVENT0("cc",
                 "SchedulerUnitTest::InitializeOutputSurfaceAndFirstCommit");
    DCHECK(scheduler_);

    // Check the client doesn't have any actions queued when calling this
    // function.
    EXPECT_NO_ACTION(client_);
    EXPECT_FALSE(scheduler_->begin_frames_expected());

    // Start the initial output surface creation.
    scheduler_->SetVisible(true);
    scheduler_->SetCanDraw(true);
    EXPECT_SINGLE_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_);

    client_->Reset();

    // We don't see anything happening until the first impl frame.
    scheduler_->DidCreateAndInitializeOutputSurface();
    scheduler_->SetNeedsBeginMainFrame();
    EXPECT_TRUE(scheduler_->begin_frames_expected());
    EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
    client_->Reset();

    {
      SCOPED_TRACE("Do first frame to commit after initialize.");
      AdvanceFrame();

      scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
      scheduler_->NotifyReadyToCommit();
      scheduler_->NotifyReadyToActivate();
      scheduler_->NotifyReadyToDraw();

      EXPECT_FALSE(scheduler_->CommitPending());

      if (scheduler_settings_.using_synchronous_renderer_compositor) {
        scheduler_->SetNeedsRedraw();
        bool resourceless_software_draw = false;
        scheduler_->OnDrawForOutputSurface(resourceless_software_draw);
      } else {
        // Run the posted deadline task.
        EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
        task_runner_->RunTasksWhile(client_->ImplFrameDeadlinePending(true));
      }

      EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
    }

    client_->Reset();

    {
      SCOPED_TRACE(
          "Run second frame so Scheduler calls SetNeedsBeginFrame(false).");
      AdvanceFrame();

      if (!scheduler_settings_.using_synchronous_renderer_compositor) {
        // Run the posted deadline task.
        EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
        task_runner_->RunTasksWhile(client_->ImplFrameDeadlinePending(true));
      }

      EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
    }

    EXPECT_FALSE(scheduler_->begin_frames_expected());
    client_->Reset();
  }

  // As this function contains EXPECT macros, to allow debugging it should be
  // called inside EXPECT_SCOPED like so;
  //   EXPECT_SCOPED(client.AdvanceFrame());
  void AdvanceFrame() {
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"),
                 "FakeSchedulerClient::AdvanceFrame");
    // Consume any previous deadline first, if no deadline is currently
    // pending, ImplFrameDeadlinePending will return false straight away and we
    // will run no tasks.
    task_runner_->RunTasksWhile(client_->ImplFrameDeadlinePending(true));
    EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

    // Send the next BeginFrame message if using an external source, otherwise
    // it will be already in the task queue.
    if (scheduler_->begin_frame_source() ==
        fake_external_begin_frame_source_.get()) {
      EXPECT_TRUE(scheduler_->begin_frames_expected());
      SendNextBeginFrame();
    }

    if (!scheduler_->settings().using_synchronous_renderer_compositor) {
      // Then run tasks until new deadline is scheduled.
      EXPECT_TRUE(task_runner_->RunTasksWhile(
          client_->ImplFrameDeadlinePending(false)));
      EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
    }
  }

  BeginFrameArgs SendNextBeginFrame() {
    DCHECK_EQ(scheduler_->begin_frame_source(),
              fake_external_begin_frame_source_.get());
    // Creep the time forward so that any BeginFrameArgs is not equal to the
    // last one otherwise we violate the BeginFrameSource contract.
    now_src_->Advance(BeginFrameArgs::DefaultInterval());
    BeginFrameArgs args =
        CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, now_src());
    fake_external_begin_frame_source_->TestOnBeginFrame(args);
    return args;
  }

  FakeExternalBeginFrameSource* fake_external_begin_frame_source() const {
    return fake_external_begin_frame_source_.get();
  }

  void CheckMainFrameSkippedAfterLateCommit(bool expect_send_begin_main_frame);
  void ImplFrameSkippedAfterLateSwapAck(bool swap_ack_before_deadline);
  void ImplFrameNotSkippedAfterLateSwapAck();
  void BeginFramesNotFromClient(bool use_external_begin_frame_source,
                                bool throttle_frame_production);
  void BeginFramesNotFromClient_SwapThrottled(
      bool use_external_begin_frame_source,
      bool throttle_frame_production);
  bool BeginMainFrameOnCriticalPath(TreePriority tree_priority,
                                    ScrollHandlerState scroll_handler_state,
                                    base::TimeDelta durations);

  std::unique_ptr<base::SimpleTestTickClock> now_src_;
  scoped_refptr<OrderedSimpleTaskRunner> task_runner_;
  std::unique_ptr<FakeExternalBeginFrameSource>
      fake_external_begin_frame_source_;
  std::unique_ptr<SyntheticBeginFrameSource> synthetic_frame_source_;
  std::unique_ptr<SyntheticBeginFrameSource> unthrottled_frame_source_;
  SchedulerSettings scheduler_settings_;
  std::unique_ptr<FakeSchedulerClient> client_;
  std::unique_ptr<TestScheduler> scheduler_;
  FakeCompositorTimingHistory* fake_compositor_timing_history_;
};

TEST_F(SchedulerTest, InitializeOutputSurfaceDoesNotBeginImplFrame) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(false);
  scheduler_->SetVisible(true);
  scheduler_->SetCanDraw(true);

  EXPECT_SINGLE_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_);
  client_->Reset();
  scheduler_->DidCreateAndInitializeOutputSurface();
  EXPECT_NO_ACTION(client_);
}

TEST_F(SchedulerTest, VideoNeedsBeginFrames) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetVideoNeedsBeginFrames(true);
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  // WillBeginImplFrame is responsible for sending BeginFrames to video.
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);

  client_->Reset();
  scheduler_->SetVideoNeedsBeginFrames(false);
  EXPECT_NO_ACTION(client_);

  client_->Reset();
  task_runner_->RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_ACTION("RemoveObserver(this)", client_, 0, 2);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 1, 2);
  EXPECT_FALSE(scheduler_->begin_frames_expected());
}

TEST_F(SchedulerTest, RequestCommit) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // If we don't swap on the deadline, we wait for the next BeginFrame.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // NotifyReadyToCommit should trigger the commit.
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // NotifyReadyToActivate should trigger the activation.
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // BeginImplFrame should prepare the draw.
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // BeginImplFrame deadline should draw.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_SINGLE_ACTION("ScheduledActionDrawAndSwapIfPossible", client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // The following BeginImplFrame deadline should SetNeedsBeginFrame(false)
  // to avoid excessive toggles.
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("RemoveObserver(this)", client_, 0, 2);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 1, 2);
  client_->Reset();
}

TEST_F(SchedulerTest, RequestCommitAfterSetDeferCommit) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetDeferCommits(true);

  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_NO_ACTION(client_);

  client_->Reset();
  task_runner().RunPendingTasks();
  // There are no pending tasks or actions.
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->begin_frames_expected());

  client_->Reset();
  scheduler_->SetDeferCommits(false);
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  // Start new BeginMainFrame after defer commit is off.
  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
}

TEST_F(SchedulerTest, DeferCommitWithRedraw) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetDeferCommits(true);

  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_NO_ACTION(client_);

  // The SetNeedsRedraw will override the SetDeferCommits(true), to allow a
  // begin frame to be needed.
  client_->Reset();
  scheduler_->SetNeedsRedraw();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  AdvanceFrame();
  // BeginMainFrame is not sent during the defer commit is on.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);

  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_SINGLE_ACTION("ScheduledActionDrawAndSwapIfPossible", client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  AdvanceFrame();
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);
}

TEST_F(SchedulerTest, RequestCommitAfterBeginMainFrameSent) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // Now SetNeedsBeginMainFrame again. Calling here means we need a second
  // commit.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_EQ(client_->num_actions_(), 0);
  client_->Reset();

  // Finish the first commit.
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // Activate it.
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // Because we just swapped, the Scheduler should also request the next
  // BeginImplFrame from the OutputSurface.
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();
  // Since another commit is needed, the next BeginImplFrame should initiate
  // the second commit.
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // Finishing the commit before the deadline should post a new deadline task
  // to trigger the deadline early.
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // On the next BeginImplFrame, verify we go back to a quiescent state and
  // no longer request BeginImplFrames.
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_FALSE(scheduler_->begin_frames_expected());
  client_->Reset();
}

class SchedulerClientThatsetNeedsDrawInsideDraw : public FakeSchedulerClient {
 public:
  SchedulerClientThatsetNeedsDrawInsideDraw()
      : FakeSchedulerClient(), request_redraws_(false) {}

  void SetRequestRedrawsInsideDraw(bool enable) { request_redraws_ = enable; }

  DrawResult ScheduledActionDrawAndSwapIfPossible() override {
    // Only SetNeedsRedraw the first time this is called
    if (request_redraws_) {
      scheduler_->SetNeedsRedraw();
    }
    return FakeSchedulerClient::ScheduledActionDrawAndSwapIfPossible();
  }

  DrawResult ScheduledActionDrawAndSwapForced() override {
    NOTREACHED();
    return DRAW_SUCCESS;
  }

 private:
  bool request_redraws_;
};

// Tests for two different situations:
// 1. the scheduler dropping SetNeedsRedraw requests that happen inside
//    a ScheduledActionDrawAndSwap
// 2. the scheduler drawing twice inside a single tick
TEST_F(SchedulerTest, RequestRedrawInsideDraw) {
  SchedulerClientThatsetNeedsDrawInsideDraw* client =
      new SchedulerClientThatsetNeedsDrawInsideDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);
  client->SetRequestRedrawsInsideDraw(true);

  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_EQ(0, client->num_draws());

  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  client->SetRequestRedrawsInsideDraw(false);

  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client_->num_draws());
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  // We stop requesting BeginImplFrames after a BeginImplFrame where we don't
  // swap.
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client->num_draws());
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(client->needs_begin_frames());
}

// Test that requesting redraw inside a failed draw doesn't lose the request.
TEST_F(SchedulerTest, RequestRedrawInsideFailedDraw) {
  SchedulerClientThatsetNeedsDrawInsideDraw* client =
      new SchedulerClientThatsetNeedsDrawInsideDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);

  client->SetRequestRedrawsInsideDraw(true);
  client->SetDrawWillHappen(false);

  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_EQ(0, client->num_draws());

  // Fail the draw.
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());

  // We have a commit pending and the draw failed, and we didn't lose the redraw
  // request.
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  client->SetRequestRedrawsInsideDraw(false);

  // Fail the draw again.
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client->num_draws());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  // Draw successfully.
  client->SetDrawWillHappen(true);
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(3, client->num_draws());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());
}

class SchedulerClientThatSetNeedsBeginMainFrameInsideDraw
    : public FakeSchedulerClient {
 public:
  SchedulerClientThatSetNeedsBeginMainFrameInsideDraw()
      : set_needs_commit_on_next_draw_(false) {}

  DrawResult ScheduledActionDrawAndSwapIfPossible() override {
    // Only SetNeedsBeginMainFrame the first time this is called
    if (set_needs_commit_on_next_draw_) {
      scheduler_->SetNeedsBeginMainFrame();
      set_needs_commit_on_next_draw_ = false;
    }
    return FakeSchedulerClient::ScheduledActionDrawAndSwapIfPossible();
  }

  DrawResult ScheduledActionDrawAndSwapForced() override {
    NOTREACHED();
    return DRAW_SUCCESS;
  }

  void SetNeedsBeginMainFrameOnNextDraw() {
    set_needs_commit_on_next_draw_ = true;
  }

 private:
  bool set_needs_commit_on_next_draw_;
};

// Tests for the scheduler infinite-looping on SetNeedsBeginMainFrame requests
// that happen inside a ScheduledActionDrawAndSwap
TEST_F(SchedulerTest, RequestCommitInsideDraw) {
  SchedulerClientThatSetNeedsBeginMainFrameInsideDraw* client =
      new SchedulerClientThatSetNeedsBeginMainFrameInsideDraw;

  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);

  EXPECT_FALSE(client->needs_begin_frames());
  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_EQ(0, client->num_draws());
  EXPECT_TRUE(client->needs_begin_frames());

  client->SetNeedsBeginMainFrameOnNextDraw();
  EXPECT_SCOPED(AdvanceFrame());
  client->SetNeedsBeginMainFrameOnNextDraw();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(client->needs_begin_frames());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();

  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client->num_draws());

  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->CommitPending());
  EXPECT_TRUE(client->needs_begin_frames());

  // We stop requesting BeginImplFrames after a BeginImplFrame where we don't
  // swap.
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client->num_draws());
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->CommitPending());
  EXPECT_FALSE(client->needs_begin_frames());
}

// Tests that when a draw fails then the pending commit should not be dropped.
TEST_F(SchedulerTest, RequestCommitInsideFailedDraw) {
  SchedulerClientThatsetNeedsDrawInsideDraw* client =
      new SchedulerClientThatsetNeedsDrawInsideDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);

  client->SetDrawWillHappen(false);

  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_EQ(0, client->num_draws());

  // Fail the draw.
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());

  // We have a commit pending and the draw failed, and we didn't lose the commit
  // request.
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  // Fail the draw again.
  EXPECT_SCOPED(AdvanceFrame());

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client->num_draws());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  // Draw successfully.
  client->SetDrawWillHappen(true);
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(3, client->num_draws());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());
}

TEST_F(SchedulerTest, NoSwapWhenDrawFails) {
  SchedulerClientThatSetNeedsBeginMainFrameInsideDraw* client =
      new SchedulerClientThatSetNeedsBeginMainFrameInsideDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);

  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_EQ(0, client->num_draws());

  // Draw successfully, this starts a new frame.
  client->SetNeedsBeginMainFrameOnNextDraw();
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());

  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(client->needs_begin_frames());

  // Fail to draw, this should not start a frame.
  client->SetDrawWillHappen(false);
  client->SetNeedsBeginMainFrameOnNextDraw();
  EXPECT_SCOPED(AdvanceFrame());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(2, client->num_draws());
}

class SchedulerClientNeedsPrepareTilesInDraw : public FakeSchedulerClient {
 public:
  DrawResult ScheduledActionDrawAndSwapIfPossible() override {
    scheduler_->SetNeedsPrepareTiles();
    return FakeSchedulerClient::ScheduledActionDrawAndSwapIfPossible();
  }
};

// Test prepare tiles is independant of draws.
TEST_F(SchedulerTest, PrepareTiles) {
  SchedulerClientNeedsPrepareTilesInDraw* client =
      new SchedulerClientNeedsPrepareTilesInDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);

  // Request both draw and prepare tiles. PrepareTiles shouldn't
  // be trigged until BeginImplFrame.
  client->Reset();
  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_TRUE(scheduler_->PrepareTilesPending());
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_EQ(0, client->num_draws());
  EXPECT_FALSE(client->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(client->HasAction("ScheduledActionDrawAndSwapIfPossible"));

  // We have no immediate actions to perform, so the BeginImplFrame should post
  // the deadline task.
  client->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  // On the deadline, the actions should have occured in the right order.
  client->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());
  EXPECT_TRUE(client->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_TRUE(client->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_LT(client->ActionIndex("ScheduledActionDrawAndSwapIfPossible"),
            client->ActionIndex("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // Request a draw. We don't need a PrepareTiles yet.
  client->Reset();
  scheduler_->SetNeedsRedraw();
  EXPECT_TRUE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_EQ(0, client->num_draws());

  // We have no immediate actions to perform, so the BeginImplFrame should post
  // the deadline task.
  client->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  // Draw. The draw will trigger SetNeedsPrepareTiles, and
  // then the PrepareTiles action will be triggered after the Draw.
  // Afterwards, neither a draw nor PrepareTiles are pending.
  client->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client->num_draws());
  EXPECT_TRUE(client->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_TRUE(client->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_LT(client->ActionIndex("ScheduledActionDrawAndSwapIfPossible"),
            client->ActionIndex("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // We need a BeginImplFrame where we don't swap to go idle.
  client->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("RemoveObserver(this)", client_, 0, 2);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 1, 2);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_EQ(0, client->num_draws());

  // Now trigger a PrepareTiles outside of a draw. We will then need
  // a begin-frame for the PrepareTiles, but we don't need a draw.
  client->Reset();
  EXPECT_FALSE(client->needs_begin_frames());
  scheduler_->SetNeedsPrepareTiles();
  EXPECT_TRUE(client->needs_begin_frames());
  EXPECT_TRUE(scheduler_->PrepareTilesPending());
  EXPECT_FALSE(scheduler_->RedrawPending());

  // BeginImplFrame. There will be no draw, only PrepareTiles.
  client->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(0, client->num_draws());
  EXPECT_FALSE(client->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_TRUE(client->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
}

// Test that PrepareTiles only happens once per frame.  If an external caller
// initiates it, then the state machine should not PrepareTiles on that frame.
TEST_F(SchedulerTest, PrepareTilesOncePerFrame) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // If DidPrepareTiles during a frame, then PrepareTiles should not occur
  // again.
  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  EXPECT_TRUE(scheduler_->PrepareTilesPending());
  scheduler_->WillPrepareTiles();
  scheduler_->DidPrepareTiles();  // An explicit PrepareTiles.
  EXPECT_FALSE(scheduler_->PrepareTilesPending());

  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client_->num_draws());
  EXPECT_TRUE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_FALSE(client_->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // Next frame without DidPrepareTiles should PrepareTiles with draw.
  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client_->num_draws());
  EXPECT_TRUE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_TRUE(client_->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_LT(client_->ActionIndex("ScheduledActionDrawAndSwapIfPossible"),
            client_->ActionIndex("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // If we get another DidPrepareTiles within the same frame, we should
  // not PrepareTiles on the next frame.
  scheduler_->WillPrepareTiles();
  scheduler_->DidPrepareTiles();  // An explicit PrepareTiles.
  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  EXPECT_TRUE(scheduler_->PrepareTilesPending());

  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client_->num_draws());
  EXPECT_TRUE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_FALSE(client_->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // If we get another DidPrepareTiles, we should not PrepareTiles on the next
  // frame. This verifies we don't alternate calling PrepareTiles once and
  // twice.
  EXPECT_TRUE(scheduler_->PrepareTilesPending());
  scheduler_->WillPrepareTiles();
  scheduler_->DidPrepareTiles();  // An explicit PrepareTiles.
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  EXPECT_TRUE(scheduler_->PrepareTilesPending());

  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client_->num_draws());
  EXPECT_TRUE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_FALSE(client_->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // Next frame without DidPrepareTiles should PrepareTiles with draw.
  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client_->num_draws());
  EXPECT_TRUE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_TRUE(client_->HasAction("ScheduledActionPrepareTiles"));
  EXPECT_LT(client_->ActionIndex("ScheduledActionDrawAndSwapIfPossible"),
            client_->ActionIndex("ScheduledActionPrepareTiles"));
  EXPECT_FALSE(scheduler_->RedrawPending());
  EXPECT_FALSE(scheduler_->PrepareTilesPending());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
}

TEST_F(SchedulerTest, PrepareTilesFunnelResetOnVisibilityChange) {
  std::unique_ptr<SchedulerClientNeedsPrepareTilesInDraw> client =
      base::WrapUnique(new SchedulerClientNeedsPrepareTilesInDraw);
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(std::move(client), true);

  // Simulate a few visibility changes and associated PrepareTiles.
  for (int i = 0; i < 10; i++) {
    scheduler_->SetVisible(false);
    scheduler_->WillPrepareTiles();
    scheduler_->DidPrepareTiles();

    scheduler_->SetVisible(true);
    scheduler_->WillPrepareTiles();
    scheduler_->DidPrepareTiles();
  }

  client_->Reset();
  scheduler_->SetNeedsRedraw();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  AdvanceFrame();
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionPrepareTiles", client_, 1, 2);
}

TEST_F(SchedulerTest, TriggerBeginFrameDeadlineEarly) {
  SchedulerClientNeedsPrepareTilesInDraw* client =
      new SchedulerClientNeedsPrepareTilesInDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(base::WrapUnique(client), true);

  scheduler_->SetNeedsRedraw();
  EXPECT_SCOPED(AdvanceFrame());

  // The deadline should be zero since there is no work other than drawing
  // pending.
  EXPECT_EQ(base::TimeTicks(), client->posted_begin_impl_frame_deadline());
}

TEST_F(SchedulerTest, WaitForReadyToDrawDoNotPostDeadline) {
  SchedulerClientNeedsPrepareTilesInDraw* client =
      new SchedulerClientNeedsPrepareTilesInDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  scheduler_settings_.commit_to_active_tree = true;
  SetUpScheduler(base::WrapUnique(client), true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  // Begin new frame.
  EXPECT_SCOPED(AdvanceFrame());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);

  client_->Reset();
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);

  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);

  // Scheduler won't post deadline in the mode.
  client_->Reset();
  task_runner().RunPendingTasks();  // Try to run posted deadline.
  // There is no posted deadline.
  EXPECT_NO_ACTION(client_);

  // Scheduler received ready to draw signal, and posted deadline.
  scheduler_->NotifyReadyToDraw();
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_EQ(1, client_->num_draws());
  EXPECT_TRUE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
}

TEST_F(SchedulerTest, WaitForReadyToDrawCancelledWhenLostOutputSurface) {
  SchedulerClientNeedsPrepareTilesInDraw* client =
      new SchedulerClientNeedsPrepareTilesInDraw;
  scheduler_settings_.use_external_begin_frame_source = true;
  scheduler_settings_.commit_to_active_tree = true;
  SetUpScheduler(base::WrapUnique(client), true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  // Begin new frame.
  EXPECT_SCOPED(AdvanceFrame());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);

  client_->Reset();
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);

  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);

  // Scheduler won't post deadline in the mode.
  client_->Reset();
  task_runner().RunPendingTasks();  // Try to run posted deadline.
  // There is no posted deadline.
  EXPECT_NO_ACTION(client_);

  // Scheduler loses output surface, and stops waiting for ready to draw signal.
  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
}

void SchedulerTest::CheckMainFrameSkippedAfterLateCommit(
    bool expect_send_begin_main_frame) {
  // Impl thread hits deadline before commit finishes.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_ACTION("AddObserver(this)", client_, 0, 5);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 5);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 5);
  EXPECT_ACTION("ScheduledActionCommit", client_, 3, 5);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 4, 5);
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());

  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_EQ(expect_send_begin_main_frame,
            scheduler_->MainThreadMissedLastDeadline());
  EXPECT_TRUE(client_->HasAction("WillBeginImplFrame"));
  EXPECT_EQ(expect_send_begin_main_frame,
            client_->HasAction("ScheduledActionSendBeginMainFrame"));
}

TEST_F(SchedulerTest, MainFrameSkippedAfterLateCommit) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  bool expect_send_begin_main_frame = false;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

// Response times of BeginMainFrame's without the critical path flag set
// should not affect whether we recover latency or not.
TEST_F(SchedulerTest,
       MainFrameSkippedAfterLateCommit_LongMainFrameQueueDurationNotCritical) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameQueueDurationNotCriticalEstimate(kSlowDuration);

  bool expect_send_begin_main_frame = false;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

// Response times of BeginMainFrame's with the critical path flag set
// should affect whether we recover latency or not.
TEST_F(SchedulerTest,
       MainFrameNotSkippedAfterLateCommit_LongMainFrameQueueDurationCritical) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameQueueDurationCriticalEstimate(kSlowDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameQueueDurationNotCriticalEstimate(kSlowDuration);

  bool expect_send_begin_main_frame = true;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

TEST_F(SchedulerTest,
       MainFrameNotSkippedAfterLateCommitInPreferImplLatencyMode) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  scheduler_->SetTreePrioritiesAndScrollState(
      SMOOTHNESS_TAKES_PRIORITY,
      ScrollHandlerState::SCROLL_DOES_NOT_AFFECT_SCROLL_HANDLER);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  bool expect_send_begin_main_frame = true;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

TEST_F(SchedulerTest,
       MainFrameNotSkippedAfterLateCommit_CommitEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameStartToCommitDurationEstimate(kSlowDuration);

  bool expect_send_begin_main_frame = true;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

TEST_F(SchedulerTest,
       MainFrameNotSkippedAfterLateCommit_ReadyToActivateEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_->SetCommitToReadyToActivateDurationEstimate(
      kSlowDuration);

  bool expect_send_begin_main_frame = true;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

TEST_F(SchedulerTest,
       MainFrameNotSkippedAfterLateCommit_ActivateEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_->SetActivateDurationEstimate(kSlowDuration);

  bool expect_send_begin_main_frame = true;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

TEST_F(SchedulerTest, MainFrameNotSkippedAfterLateCommit_DrawEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_->SetDrawDurationEstimate(kSlowDuration);

  bool expect_send_begin_main_frame = true;
  EXPECT_SCOPED(
      CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
}

// If the BeginMainFrame aborts, it doesn't actually insert a frame into the
// queue, which means there is no latency to recover.
TEST_F(SchedulerTest, MainFrameNotSkippedAfterLateBeginMainFrameAbort) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // Use fast estimates so we think we can recover latency if needed.
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  // Impl thread hits deadline before BeginMainFrame aborts.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("AddObserver(this)", client_, 0, 3);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 3);
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());

  // After aborting the frame, make sure we don't skip the
  // next BeginMainFrame.
  client_->Reset();
  scheduler_->BeginMainFrameAborted(CommitEarlyOutReason::FINISHED_NO_UPDATES);
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(client_->HasAction("WillBeginImplFrame"));
  EXPECT_TRUE(client_->HasAction("ScheduledActionSendBeginMainFrame"));
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
}

// If the BeginMainFrame aborts, it doesn't actually insert a frame into the
// queue, which means there is no latency to recover.
TEST_F(SchedulerTest, MainFrameNotSkippedAfterCanDrawChanges) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // Use fast estimates so we think we can recover latency if needed.
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  // Impl thread hits deadline before BeginMainFrame aborts.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("AddObserver(this)", client_, 0, 3);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 3);
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());

  // Make us abort the upcoming draw.
  client_->Reset();
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 2);
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->SetCanDraw(false);
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

  // Make CanDraw true after activation.
  client_->Reset();
  scheduler_->SetCanDraw(true);
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

  // Make sure we don't skip the next BeginMainFrame.
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(client_->HasAction("WillBeginImplFrame"));
  EXPECT_TRUE(client_->HasAction("ScheduledActionSendBeginMainFrame"));
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
}

void SchedulerTest::ImplFrameSkippedAfterLateSwapAck(
    bool swap_ack_before_deadline) {
  // To get into a high latency state, this test disables automatic swap acks.
  client_->SetAutomaticSwapAck(false);

  // Draw and swap for first BeginFrame
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  SendNextBeginFrame();
  EXPECT_ACTION("AddObserver(this)", client_, 0, 3);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 3);

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 3);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 2, 3);

  // Verify we skip every other frame if the swap ack consistently
  // comes back late.
  for (int i = 0; i < 10; i++) {
    // Not calling scheduler_->DidSwapBuffersComplete() until after next
    // BeginImplFrame puts the impl thread in high latency mode.
    client_->Reset();
    scheduler_->SetNeedsBeginMainFrame();
    scheduler_->SetNeedsRedraw();
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
    SendNextBeginFrame();
    // Verify that we skip the BeginImplFrame
    EXPECT_NO_ACTION(client_);
    EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

    // Verify that we do not perform any actions after we are no longer
    // swap throttled.
    client_->Reset();
    if (swap_ack_before_deadline) {
      // It shouldn't matter if the swap ack comes back before the deadline...
      scheduler_->DidSwapBuffersComplete();
      task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
    } else {
      // ... or after the deadline.
      task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
      scheduler_->DidSwapBuffersComplete();
    }
    EXPECT_NO_ACTION(client_);

    // Verify that we start the next BeginImplFrame and continue normally
    // after having just skipped a BeginImplFrame.
    client_->Reset();
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
    SendNextBeginFrame();
    EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
    EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);

    client_->Reset();
    scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
    scheduler_->NotifyReadyToCommit();
    scheduler_->NotifyReadyToActivate();
    task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
    EXPECT_ACTION("ScheduledActionCommit", client_, 0, 3);
    EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 3);
    EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 2, 3);
  }
}

TEST_F(SchedulerTest,
       ImplFrameSkippedAfterLateSwapAck_FastEstimates_SwapAckThenDeadline) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  bool swap_ack_before_deadline = true;
  EXPECT_SCOPED(ImplFrameSkippedAfterLateSwapAck(swap_ack_before_deadline));
}

TEST_F(SchedulerTest,
       ImplFrameSkippedAfterLateSwapAck_FastEstimates_DeadlineThenSwapAck) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  bool swap_ack_before_deadline = false;
  EXPECT_SCOPED(ImplFrameSkippedAfterLateSwapAck(swap_ack_before_deadline));
}

TEST_F(SchedulerTest,
       ImplFrameSkippedAfterLateSwapAck_LongMainFrameQueueDurationNotCritical) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameQueueDurationNotCriticalEstimate(kSlowDuration);

  bool swap_ack_before_deadline = false;
  EXPECT_SCOPED(ImplFrameSkippedAfterLateSwapAck(swap_ack_before_deadline));
}

TEST_F(SchedulerTest,
       ImplFrameSkippedAfterLateSwapAck_ImplLatencyTakesPriority) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // Even if every estimate related to the main thread is slow, we should
  // still expect to recover impl thread latency if the draw is fast and we
  // are in impl latency takes priority.
  scheduler_->SetTreePrioritiesAndScrollState(
      SMOOTHNESS_TAKES_PRIORITY,
      ScrollHandlerState::SCROLL_DOES_NOT_AFFECT_SCROLL_HANDLER);
  fake_compositor_timing_history_->SetAllEstimatesTo(kSlowDuration);
  fake_compositor_timing_history_->SetDrawDurationEstimate(kFastDuration);

  bool swap_ack_before_deadline = false;
  EXPECT_SCOPED(ImplFrameSkippedAfterLateSwapAck(swap_ack_before_deadline));
}

TEST_F(SchedulerTest,
       ImplFrameSkippedAfterLateSwapAck_OnlyImplSideUpdatesExpected) {
  // This tests that we recover impl thread latency when there are no commits.
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // To get into a high latency state, this test disables automatic swap acks.
  client_->SetAutomaticSwapAck(false);

  // Even if every estimate related to the main thread is slow, we should
  // still expect to recover impl thread latency if there are no commits from
  // the main thread.
  fake_compositor_timing_history_->SetAllEstimatesTo(kSlowDuration);
  fake_compositor_timing_history_->SetDrawDurationEstimate(kFastDuration);

  // Draw and swap for first BeginFrame
  client_->Reset();
  scheduler_->SetNeedsRedraw();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  SendNextBeginFrame();
  EXPECT_ACTION("AddObserver(this)", client_, 0, 2);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 2);

  client_->Reset();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_SINGLE_ACTION("ScheduledActionDrawAndSwapIfPossible", client_);

  // Verify we skip every other frame if the swap ack consistently
  // comes back late.
  for (int i = 0; i < 10; i++) {
    // Not calling scheduler_->DidSwapBuffersComplete() until after next
    // BeginImplFrame puts the impl thread in high latency mode.
    client_->Reset();
    scheduler_->SetNeedsRedraw();
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
    SendNextBeginFrame();
    // Verify that we skip the BeginImplFrame
    EXPECT_NO_ACTION(client_);
    EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

    // Verify that we do not perform any actions after we are no longer
    // swap throttled.
    client_->Reset();
    scheduler_->DidSwapBuffersComplete();
    EXPECT_NO_ACTION(client_);

    // Verify that we start the next BeginImplFrame and continue normally
    // after having just skipped a BeginImplFrame.
    client_->Reset();
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
    SendNextBeginFrame();
    EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);

    client_->Reset();
    // Deadline should be immediate.
    EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
    task_runner().RunUntilTime(now_src_->NowTicks());
    EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
    EXPECT_SINGLE_ACTION("ScheduledActionDrawAndSwapIfPossible", client_);
  }
}

void SchedulerTest::ImplFrameNotSkippedAfterLateSwapAck() {
  // To get into a high latency state, this test disables automatic swap acks.
  client_->SetAutomaticSwapAck(false);

  // Draw and swap for first BeginFrame
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  SendNextBeginFrame();
  EXPECT_ACTION("AddObserver(this)", client_, 0, 3);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 3);

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 3);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 2, 3);

  // Verify impl thread consistently operates in high latency mode
  // without skipping any frames.
  for (int i = 0; i < 10; i++) {
    // Not calling scheduler_->DidSwapBuffersComplete() until after next frame
    // puts the impl thread in high latency mode.
    client_->Reset();
    scheduler_->SetNeedsBeginMainFrame();
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
    SendNextBeginFrame();
    EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);
    EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
    EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

    client_->Reset();
    scheduler_->DidSwapBuffersComplete();
    scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
    scheduler_->NotifyReadyToCommit();
    scheduler_->NotifyReadyToActivate();
    task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));

    // Verify that we don't skip the actions of the BeginImplFrame
    EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 0, 4);
    EXPECT_ACTION("ScheduledActionCommit", client_, 1, 4);
    EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 2, 4);
    EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 3, 4);
  }
}

TEST_F(
    SchedulerTest,
    ImplFrameNotSkippedAfterLateSwapAck_MainFrameQueueDurationCriticalTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameQueueDurationCriticalEstimate(kSlowDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameQueueDurationNotCriticalEstimate(kSlowDuration);
  EXPECT_SCOPED(ImplFrameNotSkippedAfterLateSwapAck());
}

TEST_F(SchedulerTest,
       ImplFrameNotSkippedAfterLateSwapAck_CommitEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_
      ->SetBeginMainFrameStartToCommitDurationEstimate(kSlowDuration);
  EXPECT_SCOPED(ImplFrameNotSkippedAfterLateSwapAck());
}

TEST_F(SchedulerTest,
       ImplFrameNotSkippedAfterLateSwapAck_ReadyToActivateEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_->SetCommitToReadyToActivateDurationEstimate(
      kSlowDuration);
  EXPECT_SCOPED(ImplFrameNotSkippedAfterLateSwapAck());
}

TEST_F(SchedulerTest,
       ImplFrameNotSkippedAfterLateSwapAck_ActivateEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_->SetActivateDurationEstimate(kSlowDuration);
  EXPECT_SCOPED(ImplFrameNotSkippedAfterLateSwapAck());
}

TEST_F(SchedulerTest, ImplFrameNotSkippedAfterLateSwapAck_DrawEstimateTooLong) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
  fake_compositor_timing_history_->SetDrawDurationEstimate(kSlowDuration);
  EXPECT_SCOPED(ImplFrameNotSkippedAfterLateSwapAck());
}

TEST_F(SchedulerTest,
       MainFrameThenImplFrameSkippedAfterLateCommitAndLateSwapAck) {
  // Set up client with custom estimates.
  // This test starts off with expensive estimates to prevent latency recovery
  // initially, then lowers the estimates to enable it once both the main
  // and impl threads are in a high latency mode.
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);
  fake_compositor_timing_history_->SetAllEstimatesTo(kSlowDuration);

  // To get into a high latency state, this test disables automatic swap acks.
  client_->SetAutomaticSwapAck(false);

  // Impl thread hits deadline before commit finishes to make
  // MainThreadMissedLastDeadline true
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());

  EXPECT_ACTION("AddObserver(this)", client_, 0, 5);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 5);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 5);
  EXPECT_ACTION("ScheduledActionCommit", client_, 3, 5);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 4, 5);

  // Draw and swap for first commit, start second commit.
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();

  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 5);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 5);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 2, 5);
  EXPECT_ACTION("ScheduledActionCommit", client_, 3, 5);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 4, 5);

  // Don't call scheduler_->DidSwapBuffersComplete() until after next frame
  // to put the impl thread in a high latency mode.
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));

  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  // Note: BeginMainFrame and swap are skipped here because of
  // swap ack backpressure, not because of latency recovery.
  EXPECT_FALSE(client_->HasAction("ScheduledActionSendBeginMainFrame"));
  EXPECT_FALSE(client_->HasAction("ScheduledActionDrawAndSwapIfPossible"));
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());

  // Lower estimates so that the scheduler will attempt latency recovery.
  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);

  // Now that both threads are in a high latency mode, make sure we
  // skip the BeginMainFrame, then the BeginImplFrame, but not both
  // at the same time.

  // Verify we skip BeginMainFrame first.
  client_->Reset();
  // Previous commit request is still outstanding.
  EXPECT_TRUE(scheduler_->NeedsBeginMainFrame());
  EXPECT_TRUE(scheduler_->SwapThrottled());
  SendNextBeginFrame();
  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->DidSwapBuffersComplete();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));

  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 1, 2);

  // Verify we skip the BeginImplFrame second.
  client_->Reset();
  // Previous commit request is still outstanding.
  EXPECT_TRUE(scheduler_->NeedsBeginMainFrame());
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  SendNextBeginFrame();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->DidSwapBuffersComplete();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

  EXPECT_NO_ACTION(client_);

  // Then verify we operate in a low latency mode.
  client_->Reset();
  // Previous commit request is still outstanding.
  EXPECT_TRUE(scheduler_->NeedsBeginMainFrame());
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  SendNextBeginFrame();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
  scheduler_->DidSwapBuffersComplete();
  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());

  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 5);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 5);
  EXPECT_ACTION("ScheduledActionCommit", client_, 2, 5);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 3, 5);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 4, 5);
}

TEST_F(
    SchedulerTest,
    Deadlock_CommitMakesProgressWhileSwapTrottledAndActiveTreeNeedsFirstDraw) {
  // NPAPI plugins on Windows block the Browser UI thread on the Renderer main
  // thread. This prevents the scheduler from receiving any pending swap acks.

  scheduler_settings_.use_external_begin_frame_source = true;
  scheduler_settings_.main_frame_while_swap_throttled_enabled = true;
  SetUpScheduler(true);

  // Disables automatic swap acks so this test can force swap ack throttling
  // to simulate a blocked Browser ui thread.
  client_->SetAutomaticSwapAck(false);

  // Get a new active tree in main-thread high latency mode and put us
  // in a swap throttled state.
  client_->Reset();
  EXPECT_FALSE(scheduler_->CommitPending());
  scheduler_->SetNeedsBeginMainFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_FALSE(scheduler_->CommitPending());
  EXPECT_ACTION("AddObserver(this)", client_, 0, 6);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 6);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 6);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 3, 6);
  EXPECT_ACTION("ScheduledActionCommit", client_, 4, 6);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 5, 6);

  // Make sure that we can finish the next commit even while swap throttled.
  client_->Reset();
  EXPECT_FALSE(scheduler_->CommitPending());
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SCOPED(AdvanceFrame());
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 3);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionCommit", client_, 2, 3);

  // Make sure we do not send a BeginMainFrame while swap throttled and
  // we have both a pending tree and an active tree.
  client_->Reset();
  EXPECT_FALSE(scheduler_->CommitPending());
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_FALSE(scheduler_->CommitPending());
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
}

TEST_F(
    SchedulerTest,
    CommitMakesProgressWhenIdleAndHasPendingTreeAndActiveTreeNeedsFirstDraw) {
  // This verifies we don't block commits longer than we need to
  // for performance reasons - not deadlock reasons.

  // Since we are simulating a long commit, set up a client with draw duration
  // estimates that prevent skipping main frames to get to low latency mode.
  scheduler_settings_.use_external_begin_frame_source = true;
  scheduler_settings_.main_frame_while_swap_throttled_enabled = true;
  scheduler_settings_.main_frame_before_activation_enabled = true;
  SetUpScheduler(true);

  // Disables automatic swap acks so this test can force swap ack throttling
  // to simulate a blocked Browser ui thread.
  client_->SetAutomaticSwapAck(false);

  // Start a new commit in main-thread high latency mode and hold off on
  // activation.
  client_->Reset();
  EXPECT_FALSE(scheduler_->CommitPending());
  scheduler_->SetNeedsBeginMainFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  scheduler_->DidSwapBuffersComplete();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_FALSE(scheduler_->CommitPending());
  EXPECT_ACTION("AddObserver(this)", client_, 0, 5);
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 5);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 5);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 3, 5);
  EXPECT_ACTION("ScheduledActionCommit", client_, 4, 5);

  // Start another commit while we still have an active tree.
  client_->Reset();
  EXPECT_FALSE(scheduler_->CommitPending());
  scheduler_->SetNeedsBeginMainFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_TRUE(scheduler_->CommitPending());
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  scheduler_->DidSwapBuffersComplete();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 3);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 2, 3);

  // Can't commit yet because there's still a pending tree.
  client_->Reset();
  scheduler_->NotifyReadyToCommit();
  EXPECT_NO_ACTION(client_);

  // Activate the pending tree, which also unblocks the commit immediately
  // while we are in an idle state.
  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionCommit", client_, 1, 2);
}

TEST_F(SchedulerTest, BeginRetroFrame) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  // Create a BeginFrame with a long deadline to avoid race conditions.
  // This is the first BeginFrame, which will be handled immediately.
  BeginFrameArgs args =
      CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, now_src());
  args.deadline += base::TimeDelta::FromHours(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // Queue BeginFrames while we are still handling the previous BeginFrame.
  args.frame_time += base::TimeDelta::FromSeconds(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);
  args.frame_time += base::TimeDelta::FromSeconds(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);

  // If we don't swap on the deadline, we wait for the next BeginImplFrame.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // NotifyReadyToCommit should trigger the commit.
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // NotifyReadyToActivate should trigger the activation.
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // BeginImplFrame should prepare the draw.
  task_runner().RunPendingTasks();  // Run posted BeginRetroFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // BeginImplFrame deadline should draw.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  // The following BeginImplFrame deadline should SetNeedsBeginFrame(false)
  // to avoid excessive toggles.
  task_runner().RunPendingTasks();  // Run posted BeginRetroFrame.
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("RemoveObserver(this)", client_, 0, 2);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 1, 2);
  client_->Reset();
}

TEST_F(SchedulerTest, RetroFrameDoesNotExpireTooEarly) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());

  client_->Reset();
  BeginFrameArgs retro_frame_args = SendNextBeginFrame();
  // This BeginFrame is queued up as a retro frame.
  EXPECT_NO_ACTION(client_);
  // The previous deadline is still pending.
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  // This main frame activating should schedule the (previous) deadline to
  // trigger immediately.
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 2);

  client_->Reset();
  // The deadline task should trigger causing a draw.
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);

  // Keep animating.
  client_->Reset();
  scheduler_->SetNeedsOneBeginImplFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_NO_ACTION(client_);

  // Let's advance to the retro frame's deadline.
  now_src()->Advance(retro_frame_args.deadline - now_src()->NowTicks());

  // The retro frame hasn't expired yet.
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(false));
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  // This is an immediate deadline case.
  client_->Reset();
  task_runner().RunPendingTasks();
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_SINGLE_ACTION("ScheduledActionDrawAndSwapIfPossible", client_);
}

TEST_F(SchedulerTest, RetroFrameExpiresOnTime) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());

  client_->Reset();
  BeginFrameArgs retro_frame_args = SendNextBeginFrame();
  // This BeginFrame is queued up as a retro frame.
  EXPECT_NO_ACTION(client_);
  // The previous deadline is still pending.
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  // This main frame activating should schedule the (previous) deadline to
  // trigger immediately.
  scheduler_->NotifyReadyToCommit();
  scheduler_->NotifyReadyToActivate();
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 2);

  client_->Reset();
  // The deadline task should trigger causing a draw.
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);

  // Keep animating.
  client_->Reset();
  scheduler_->SetNeedsOneBeginImplFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_NO_ACTION(client_);

  // Let's advance sufficiently past the retro frame's deadline.
  now_src()->Advance(retro_frame_args.deadline - now_src()->NowTicks() +
                     base::TimeDelta::FromMicroseconds(1));

  // The retro frame should've expired.
  EXPECT_NO_ACTION(client_);
}

TEST_F(SchedulerTest, MissedFrameDoesNotExpireTooEarly) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  BeginFrameArgs missed_frame_args =
      CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, now_src());
  missed_frame_args.type = BeginFrameArgs::MISSED;

  // Advance to the deadline.
  now_src()->Advance(missed_frame_args.deadline - now_src()->NowTicks());

  // Missed frame is handled because it's on time.
  client_->Reset();
  fake_external_begin_frame_source_->TestOnBeginFrame(missed_frame_args);
  EXPECT_TRUE(
      task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(false)));
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
}

TEST_F(SchedulerTest, MissedFrameExpiresOnTime) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  BeginFrameArgs missed_frame_args =
      CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, now_src());
  missed_frame_args.type = BeginFrameArgs::MISSED;

  // Advance sufficiently past the deadline.
  now_src()->Advance(missed_frame_args.deadline - now_src()->NowTicks() +
                     base::TimeDelta::FromMicroseconds(1));

  // Missed frame is dropped because it's too late.
  client_->Reset();
  fake_external_begin_frame_source_->TestOnBeginFrame(missed_frame_args);
  EXPECT_FALSE(
      task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(false)));
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
}

void SchedulerTest::BeginFramesNotFromClient(
    bool use_external_begin_frame_source,
    bool throttle_frame_production) {
  scheduler_settings_.use_external_begin_frame_source =
      use_external_begin_frame_source;
  scheduler_settings_.throttle_frame_production = throttle_frame_production;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame
  // without calling SetNeedsBeginFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_NO_ACTION(client_);
  client_->Reset();

  // When the client-driven BeginFrame are disabled, the scheduler posts it's
  // own BeginFrame tasks.
  task_runner().RunPendingTasks();  // Run posted BeginFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // If we don't swap on the deadline, we wait for the next BeginFrame.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // NotifyReadyToCommit should trigger the commit.
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  client_->Reset();

  // NotifyReadyToActivate should trigger the activation.
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  client_->Reset();

  // BeginImplFrame should prepare the draw.
  task_runner().RunPendingTasks();  // Run posted BeginFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // BeginImplFrame deadline should draw.
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // The following BeginImplFrame deadline should SetNeedsBeginFrame(false)
  // to avoid excessive toggles.
  task_runner().RunPendingTasks();  // Run posted BeginFrame.
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // Make sure SetNeedsBeginFrame isn't called on the client
  // when the BeginFrame is no longer needed.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_SINGLE_ACTION("SendBeginMainFrameNotExpectedSoon", client_);
  client_->Reset();
}

TEST_F(SchedulerTest, SyntheticBeginFrames) {
  bool use_external_begin_frame_source = false;
  bool throttle_frame_production = true;
  BeginFramesNotFromClient(use_external_begin_frame_source,
                           throttle_frame_production);
}

TEST_F(SchedulerTest, VSyncThrottlingDisabled) {
  bool use_external_begin_frame_source = true;
  bool throttle_frame_production = false;
  BeginFramesNotFromClient(use_external_begin_frame_source,
                           throttle_frame_production);
}

TEST_F(SchedulerTest, SyntheticBeginFrames_And_VSyncThrottlingDisabled) {
  bool use_external_begin_frame_source = false;
  bool throttle_frame_production = false;
  BeginFramesNotFromClient(use_external_begin_frame_source,
                           throttle_frame_production);
}

void SchedulerTest::BeginFramesNotFromClient_SwapThrottled(
    bool use_external_begin_frame_source,
    bool throttle_frame_production) {
  scheduler_settings_.use_external_begin_frame_source =
      use_external_begin_frame_source;
  scheduler_settings_.throttle_frame_production = throttle_frame_production;
  SetUpScheduler(true);

  scheduler_->SetEstimatedParentDrawTime(
      BeginFrameArgs::DefaultEstimatedParentDrawTime());

  // Set the draw duration estimate to zero so that deadlines are accurate.
  fake_compositor_timing_history_->SetDrawDurationEstimate(base::TimeDelta());

  // To test swap ack throttling, this test disables automatic swap acks.
  client_->SetAutomaticSwapAck(false);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  client_->Reset();
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_NO_ACTION(client_);
  client_->Reset();

  // Trigger the first BeginImplFrame and BeginMainFrame
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // NotifyReadyToCommit should trigger the pending commit.
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  client_->Reset();

  // NotifyReadyToActivate should trigger the activation and draw.
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  client_->Reset();

  // Swapping will put us into a swap throttled state.
  // Run posted deadline.
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // While swap throttled, BeginFrames should trigger BeginImplFrames,
  // but not a BeginMainFrame or draw.
  scheduler_->SetNeedsBeginMainFrame();
  scheduler_->SetNeedsRedraw();
  EXPECT_SCOPED(AdvanceFrame());  // Run posted BeginFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  base::TimeTicks before_deadline, after_deadline;

  // The deadline is set to the regular deadline.
  before_deadline = now_src()->NowTicks();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  after_deadline = now_src()->NowTicks();
  // We can't do an equality comparison here because the scheduler uses a fudge
  // factor that's an internal implementation detail.
  EXPECT_GT(after_deadline, before_deadline);
  EXPECT_LT(after_deadline,
            before_deadline + BeginFrameArgs::DefaultInterval());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  EXPECT_SCOPED(AdvanceFrame());  // Run posted BeginFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // Take us out of a swap throttled state.
  scheduler_->DidSwapBuffersComplete();
  EXPECT_SINGLE_ACTION("ScheduledActionSendBeginMainFrame", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // The deadline is set to the regular deadline.
  before_deadline = now_src()->NowTicks();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  after_deadline = now_src()->NowTicks();
  // We can't do an equality comparison here because the scheduler uses a fudge
  // factor that's an internal implementation detail.
  EXPECT_GT(after_deadline, before_deadline);
  EXPECT_LT(after_deadline,
            before_deadline + BeginFrameArgs::DefaultInterval());
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();
}

TEST_F(SchedulerTest, SyntheticBeginFrames_SwapThrottled) {
  bool use_external_begin_frame_source = false;
  bool throttle_frame_production = true;
  BeginFramesNotFromClient_SwapThrottled(use_external_begin_frame_source,
                                         throttle_frame_production);
}

TEST_F(SchedulerTest, VSyncThrottlingDisabled_SwapThrottled) {
  bool use_external_begin_frame_source = true;
  bool throttle_frame_production = false;
  BeginFramesNotFromClient_SwapThrottled(use_external_begin_frame_source,
                                         throttle_frame_production);
}

TEST_F(SchedulerTest,
       SyntheticBeginFrames_And_VSyncThrottlingDisabled_SwapThrottled) {
  bool use_external_begin_frame_source = false;
  bool throttle_frame_production = false;
  BeginFramesNotFromClient_SwapThrottled(use_external_begin_frame_source,
                                         throttle_frame_production);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceAfterOutputSurfaceIsInitialized) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(false);

  scheduler_->SetVisible(true);
  scheduler_->SetCanDraw(true);

  EXPECT_SINGLE_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_);
  client_->Reset();
  scheduler_->DidCreateAndInitializeOutputSurface();
  EXPECT_NO_ACTION(client_);

  scheduler_->DidLoseOutputSurface();
  EXPECT_SINGLE_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceAfterBeginFrameStarted) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  // RemoveObserver(this) is not called until the end of the frame.
  EXPECT_NO_ACTION(client_);

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 2);

  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
}

TEST_F(SchedulerTest,
       DidLoseOutputSurfaceAfterBeginFrameStartedWithHighLatency) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  // Do nothing when impl frame is in deadine pending state.
  EXPECT_NO_ACTION(client_);

  client_->Reset();
  // Run posted deadline.
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  // OnBeginImplFrameDeadline didn't schedule output surface creation because
  // main frame is not yet completed.
  EXPECT_ACTION("RemoveObserver(this)", client_, 0, 2);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 1, 2);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  // BeginImplFrame is not started.
  client_->Reset();
  task_runner().RunUntilTime(now_src()->NowTicks() +
                             base::TimeDelta::FromMilliseconds(10));
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_ACTION("ScheduledActionCommit", client_, 0, 3);
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 1, 3);
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 2, 3);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceAfterReadyToCommit) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);

  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  // Sync tree should be forced to activate.
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);

  // RemoveObserver(this) is not called until the end of the frame.
  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceAfterSetNeedsPrepareTiles) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsPrepareTiles();
  scheduler_->SetNeedsRedraw();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  // RemoveObserver(this) is not called until the end of the frame.
  EXPECT_NO_ACTION(client_);

  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionPrepareTiles", client_, 0, 4);
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 1, 4);
  EXPECT_ACTION("RemoveObserver(this)", client_, 2, 4);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 3, 4);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceAfterBeginRetroFramePosted) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  // Create a BeginFrame with a long deadline to avoid race conditions.
  // This is the first BeginFrame, which will be handled immediately.
  client_->Reset();
  BeginFrameArgs args =
      CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, now_src());
  args.deadline += base::TimeDelta::FromHours(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // Queue BeginFrames while we are still handling the previous BeginFrame.
  args.frame_time += base::TimeDelta::FromSeconds(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);
  args.frame_time += base::TimeDelta::FromSeconds(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);

  // If we don't swap on the deadline, we wait for the next BeginImplFrame.
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // NotifyReadyToCommit should trigger the commit.
  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // NotifyReadyToActivate should trigger the activation.
  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  EXPECT_FALSE(scheduler_->IsBeginRetroFrameArgsEmpty());
  scheduler_->DidLoseOutputSurface();
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
  EXPECT_TRUE(scheduler_->IsBeginRetroFrameArgsEmpty());

  // Posted BeginRetroFrame is aborted.
  client_->Reset();
  task_runner().RunPendingTasks();
  EXPECT_NO_ACTION(client_);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceDuringBeginRetroFrameRunning) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  // Create a BeginFrame with a long deadline to avoid race conditions.
  // This is the first BeginFrame, which will be handled immediately.
  client_->Reset();
  BeginFrameArgs args =
      CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, now_src());
  args.deadline += base::TimeDelta::FromHours(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // Queue BeginFrames while we are still handling the previous BeginFrame.
  args.frame_time += base::TimeDelta::FromSeconds(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);
  args.frame_time += base::TimeDelta::FromSeconds(1);
  fake_external_begin_frame_source()->TestOnBeginFrame(args);

  // If we don't swap on the deadline, we wait for the next BeginImplFrame.
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_NO_ACTION(client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // NotifyReadyToCommit should trigger the commit.
  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // NotifyReadyToActivate should trigger the activation.
  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // BeginImplFrame should prepare the draw.
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted BeginRetroFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  EXPECT_FALSE(scheduler_->IsBeginRetroFrameArgsEmpty());
  scheduler_->DidLoseOutputSurface();
  EXPECT_NO_ACTION(client_);
  EXPECT_TRUE(scheduler_->IsBeginRetroFrameArgsEmpty());

  // BeginImplFrame deadline should abort drawing.
  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_FALSE(scheduler_->begin_frames_expected());

  // No more BeginRetroFrame because BeginRetroFrame queue is cleared.
  client_->Reset();
  task_runner().RunPendingTasks();
  EXPECT_NO_ACTION(client_);
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceWithDelayBasedBeginFrameSource) {
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame on the next BeginImplFrame.
  EXPECT_FALSE(scheduler_->begin_frames_expected());
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  AdvanceFrame();
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // NotifyReadyToCommit should trigger the commit.
  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  // NotifyReadyToActivate should trigger the activation.
  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  // RemoveObserver(this) is not called until the end of the frame.
  EXPECT_NO_ACTION(client_);
  EXPECT_TRUE(scheduler_->begin_frames_expected());

  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 2);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 1, 2);
  EXPECT_FALSE(scheduler_->begin_frames_expected());
}

TEST_F(SchedulerTest, DidLoseOutputSurfaceWhenIdle) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);

  client_->Reset();
  scheduler_->NotifyReadyToActivate();
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);

  client_->Reset();
  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);

  // Idle time between BeginFrames.
  client_->Reset();
  scheduler_->DidLoseOutputSurface();
  EXPECT_ACTION("ScheduledActionBeginOutputSurfaceCreation", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
}

TEST_F(SchedulerTest, ScheduledActionActivateAfterBecomingInvisible) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->SetVisible(false);
  task_runner().RunPendingTasks();  // Run posted deadline.

  // Sync tree should be forced to activate.
  EXPECT_ACTION("ScheduledActionActivateSyncTree", client_, 0, 3);
  EXPECT_ACTION("RemoveObserver(this)", client_, 1, 3);
  EXPECT_ACTION("SendBeginMainFrameNotExpectedSoon", client_, 2, 3);
}

TEST_F(SchedulerTest, ScheduledActionActivateAfterBeginFrameSourcePaused) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsBeginMainFrame should begin the frame.
  scheduler_->SetNeedsBeginMainFrame();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);

  client_->Reset();
  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 2);
  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 1, 2);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
  scheduler_->NotifyReadyToCommit();
  EXPECT_SINGLE_ACTION("ScheduledActionCommit", client_);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());

  client_->Reset();
  fake_external_begin_frame_source_->SetPaused(true);
  task_runner().RunPendingTasks();  // Run posted deadline.

  // Sync tree should be forced to activate.
  EXPECT_SINGLE_ACTION("ScheduledActionActivateSyncTree", client_);
}

// Tests to ensure frame sources can be successfully changed while drawing.
TEST_F(SchedulerTest, SwitchFrameSourceToUnthrottled) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsRedraw should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsRedraw();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  scheduler_->SetNeedsRedraw();

  // Switch to an unthrottled frame source.
  scheduler_->SetBeginFrameSource(unthrottled_frame_source_.get());
  client_->Reset();

  // Unthrottled frame source will immediately begin a new frame.
  task_runner().RunPendingTasks();  // Run posted BeginFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // If we don't swap on the deadline, we wait for the next BeginFrame.
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();
}

// Tests to ensure frame sources can be successfully changed while a frame
// deadline is pending.
TEST_F(SchedulerTest, SwitchFrameSourceToUnthrottledBeforeDeadline) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  // SetNeedsRedraw should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsRedraw();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_SINGLE_ACTION("WillBeginImplFrame", client_);

  // Switch to an unthrottled frame source before the frame deadline is hit.
  scheduler_->SetBeginFrameSource(unthrottled_frame_source_.get());
  client_->Reset();

  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 2);
  // Unthrottled frame source will immediately begin a new frame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 2);
  scheduler_->SetNeedsRedraw();
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_SINGLE_ACTION("ScheduledActionDrawAndSwapIfPossible", client_);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();
}

// Tests to ensure that the active frame source can successfully be changed from
// unthrottled to throttled.
TEST_F(SchedulerTest, SwitchFrameSourceToThrottled) {
  scheduler_settings_.throttle_frame_production = false;
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsRedraw();
  EXPECT_NO_ACTION(client_);
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted BeginFrame.
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
  EXPECT_FALSE(scheduler_->BeginImplFrameDeadlinePending());
  client_->Reset();

  // Switch to a throttled frame source.
  scheduler_->SetBeginFrameSource(fake_external_begin_frame_source_.get());
  client_->Reset();

  // SetNeedsRedraw should begin the frame on the next BeginImplFrame.
  scheduler_->SetNeedsRedraw();
  task_runner().RunPendingTasks();
  EXPECT_NO_ACTION(client_);
  client_->Reset();

  EXPECT_SCOPED(AdvanceFrame());
  EXPECT_ACTION("WillBeginImplFrame", client_, 0, 1);
  EXPECT_TRUE(scheduler_->BeginImplFrameDeadlinePending());
  EXPECT_TRUE(scheduler_->begin_frames_expected());
  client_->Reset();
  task_runner().RunPendingTasks();  // Run posted deadline.
  EXPECT_ACTION("ScheduledActionDrawAndSwapIfPossible", client_, 0, 1);
}

TEST_F(SchedulerTest, SwitchFrameSourceToNullInsideDeadline) {
  scheduler_settings_.use_external_begin_frame_source = true;
  SetUpScheduler(true);

  scheduler_->SetNeedsRedraw();
  EXPECT_SINGLE_ACTION("AddObserver(this)", client_);
  client_->Reset();

  EXPECT_SCOPED(AdvanceFrame());