content/browser/renderer_host/render_widget_host_impl.cc

// Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_impl.h"

#include <utility>

#include "base/auto_reset.h"
#include "base/bind.h"
#include "base/command_line.h"
#include "base/debug/trace_event.h"
#include "base/i18n/rtl.h"
#include "base/message_loop.h"
#include "base/metrics/histogram.h"
#include "base/string_number_conversions.h"
#include "base/utf_string_conversions.h"
#include "content/browser/gpu/gpu_process_host.h"
#include "content/browser/gpu/gpu_process_host_ui_shim.h"
#include "content/browser/gpu/gpu_surface_tracker.h"
#include "content/browser/renderer_host/backing_store.h"
#include "content/browser/renderer_host/backing_store_manager.h"
#include "content/browser/renderer_host/render_process_host_impl.h"
#include "content/browser/renderer_host/render_view_host_impl.h"
#include "content/browser/renderer_host/render_widget_helper.h"
#include "content/browser/renderer_host/tap_suppression_controller.h"
#include "content/common/accessibility_messages.h"
#include "content/common/gpu/gpu_messages.h"
#include "content/common/view_messages.h"
#include "content/port/browser/render_widget_host_view_port.h"
#include "content/public/browser/native_web_keyboard_event.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/notification_types.h"
#include "content/public/browser/user_metrics.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/result_codes.h"
#include "skia/ext/image_operations.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebCompositionUnderline.h"
#include "ui/base/keycodes/keyboard_codes.h"
#include "ui/gfx/skbitmap_operations.h"
#include "webkit/glue/webcursor.h"
#include "webkit/glue/webpreferences.h"
#include "webkit/plugins/npapi/webplugin.h"

#if defined(TOOLKIT_GTK)
#include "content/browser/renderer_host/backing_store_gtk.h"
#elif defined(OS_MACOSX)
#include "content/browser/renderer_host/backing_store_mac.h"
#endif

using base::Time;
using base::TimeDelta;
using base::TimeTicks;
using WebKit::WebGestureEvent;
using WebKit::WebInputEvent;
using WebKit::WebKeyboardEvent;
using WebKit::WebMouseEvent;
using WebKit::WebMouseWheelEvent;
using WebKit::WebTextDirection;

namespace {

// How long to (synchronously) wait for the renderer to respond with a
// PaintRect message, when our backing-store is invalid, before giving up and
// returning a null or incorrectly sized backing-store from GetBackingStore.
// This timeout impacts the "choppiness" of our window resize perf.
static const int kPaintMsgTimeoutMS = 40;

// How long to wait before we consider a renderer hung.
static const int kHungRendererDelayMs = 20000;

// Returns |true| if the two wheel events should be coalesced.
bool ShouldCoalesceMouseWheelEvents(const WebMouseWheelEvent& last_event,
                                    const WebMouseWheelEvent& new_event) {
  return last_event.modifiers == new_event.modifiers &&
         last_event.scrollByPage == new_event.scrollByPage &&
         last_event.hasPreciseScrollingDeltas
             == new_event.hasPreciseScrollingDeltas &&
         last_event.phase == new_event.phase &&
         last_event.momentumPhase == new_event.momentumPhase;
}

}  // namespace

namespace content {

// static
void RenderWidgetHost::RemoveAllBackingStores() {
  BackingStoreManager::RemoveAllBackingStores();
}

// static
size_t RenderWidgetHost::BackingStoreMemorySize() {
  return BackingStoreManager::MemorySize();
}

///////////////////////////////////////////////////////////////////////////////
// RenderWidgetHostImpl

RenderWidgetHostImpl::RenderWidgetHostImpl(RenderProcessHost* process,
                                           int routing_id)
    : view_(NULL),
      renderer_initialized_(false),
      hung_renderer_delay_ms_(kHungRendererDelayMs),
      process_(process),
      routing_id_(routing_id),
      surface_id_(0),
      is_loading_(false),
      is_hidden_(false),
      is_fullscreen_(false),
      is_accelerated_compositing_active_(false),
      repaint_ack_pending_(false),
      resize_ack_pending_(false),
      should_auto_resize_(false),
      mouse_move_pending_(false),
      mouse_wheel_pending_(false),
      needs_repainting_on_restore_(false),
      is_unresponsive_(false),
      in_flight_event_count_(0),
      in_get_backing_store_(false),
      view_being_painted_(false),
      ignore_input_events_(false),
      text_direction_updated_(false),
      text_direction_(WebKit::WebTextDirectionLeftToRight),
      text_direction_canceled_(false),
      suppress_next_char_events_(false),
      pending_mouse_lock_request_(false),
      has_touch_handler_(false),
      ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
      tap_suppression_controller_(new TapSuppressionController(this)) {
  if (routing_id_ == MSG_ROUTING_NONE) {
    routing_id_ = process_->GetNextRoutingID();
    surface_id_ = GpuSurfaceTracker::Get()->AddSurfaceForRenderer(
        process_->GetID(),
        routing_id_);
  } else {
    // TODO(piman): This is a O(N) lookup, where we could forward the
    // information from the RenderWidgetHelper. The problem is that doing so
    // currently leaks outside of content all the way to chrome classes, and
    // would be a layering violation. Since we don't expect more than a few
    // hundreds of RWH, this seems acceptable. Revisit if performance become a
    // problem, for example by tracking in the RenderWidgetHelper the routing id
    // (and surface id) that have been created, but whose RWH haven't yet.
    surface_id_ = GpuSurfaceTracker::Get()->LookupSurfaceForRenderer(
        process_->GetID(),
        routing_id_);
    DCHECK(surface_id_);
  }

  process_->Attach(this, routing_id_);
  // Because the widget initializes as is_hidden_ == false,
  // tell the process host that we're alive.
  process_->WidgetRestored();
}

RenderWidgetHostImpl::~RenderWidgetHostImpl() {
  SetView(NULL);

  // Clear our current or cached backing store if either remains.
  BackingStoreManager::RemoveBackingStore(this);

  GpuSurfaceTracker::Get()->RemoveSurface(surface_id_);
  surface_id_ = 0;

  process_->Release(routing_id_);
}

// static
RenderWidgetHostImpl* RenderWidgetHostImpl::From(RenderWidgetHost* rwh) {
  return rwh->AsRenderWidgetHostImpl();
}

void RenderWidgetHostImpl::SetView(RenderWidgetHostView* view) {
  view_ = RenderWidgetHostViewPort::FromRWHV(view);

  if (!view_) {
    GpuSurfaceTracker::Get()->SetSurfaceHandle(
        surface_id_, gfx::GLSurfaceHandle());
  }
}

RenderProcessHost* RenderWidgetHostImpl::GetProcess() const {
  return process_;
}

int RenderWidgetHostImpl::GetRoutingID() const {
  return routing_id_;
}

RenderWidgetHostView* RenderWidgetHostImpl::GetView() const {
  return view_;
}

RenderWidgetHostImpl* RenderWidgetHostImpl::AsRenderWidgetHostImpl() {
  return this;
}

gfx::NativeViewId RenderWidgetHostImpl::GetNativeViewId() const {
  if (view_)
    return view_->GetNativeViewId();
  return 0;
}

gfx::GLSurfaceHandle RenderWidgetHostImpl::GetCompositingSurface() {
  if (view_)
    return view_->GetCompositingSurface();
  return gfx::GLSurfaceHandle();
}

void RenderWidgetHostImpl::CompositingSurfaceUpdated() {
  GpuSurfaceTracker::Get()->SetSurfaceHandle(
      surface_id_, GetCompositingSurface());
  process_->SurfaceUpdated(surface_id_);
}

bool RenderWidgetHostImpl::PreHandleKeyboardEvent(
    const NativeWebKeyboardEvent& event,
    bool* is_keyboard_shortcut) {
  return false;
}

void RenderWidgetHostImpl::Init() {
  DCHECK(process_->HasConnection());

  renderer_initialized_ = true;

  GpuSurfaceTracker::Get()->SetSurfaceHandle(
      surface_id_, GetCompositingSurface());

  // Send the ack along with the information on placement.
  Send(new ViewMsg_CreatingNew_ACK(routing_id_, GetNativeViewId()));
  WasResized();
}

void RenderWidgetHostImpl::Shutdown() {
  if (process_->HasConnection()) {
    // Tell the renderer object to close.
    bool rv = Send(new ViewMsg_Close(routing_id_));
    DCHECK(rv);
  }

  Destroy();
}

bool RenderWidgetHostImpl::IsRenderView() const {
  return false;
}

bool RenderWidgetHostImpl::OnMessageReceived(const IPC::Message &msg) {
  bool handled = true;
  bool msg_is_ok = true;
  IPC_BEGIN_MESSAGE_MAP_EX(RenderWidgetHostImpl, msg, msg_is_ok)
    IPC_MESSAGE_HANDLER(ViewHostMsg_RenderViewReady, OnMsgRenderViewReady)
    IPC_MESSAGE_HANDLER(ViewHostMsg_RenderViewGone, OnMsgRenderViewGone)
    IPC_MESSAGE_HANDLER(ViewHostMsg_Close, OnMsgClose)
    IPC_MESSAGE_HANDLER(ViewHostMsg_RequestMove, OnMsgRequestMove)
    IPC_MESSAGE_HANDLER(ViewHostMsg_SetTooltipText, OnMsgSetTooltipText)
    IPC_MESSAGE_HANDLER(ViewHostMsg_PaintAtSize_ACK, OnMsgPaintAtSizeAck)
    IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateRect, OnMsgUpdateRect)
    IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateIsDelayed, OnMsgUpdateIsDelayed)
    IPC_MESSAGE_HANDLER(ViewHostMsg_HandleInputEvent_ACK, OnMsgInputEventAck)
    IPC_MESSAGE_HANDLER(ViewHostMsg_Focus, OnMsgFocus)
    IPC_MESSAGE_HANDLER(ViewHostMsg_Blur, OnMsgBlur)
    IPC_MESSAGE_HANDLER(ViewHostMsg_DidChangeNumTouchEvents,
                        OnMsgDidChangeNumTouchEvents)
    IPC_MESSAGE_HANDLER(ViewHostMsg_SetCursor, OnMsgSetCursor)
    IPC_MESSAGE_HANDLER(ViewHostMsg_TextInputStateChanged,
                        OnMsgTextInputStateChanged)
    IPC_MESSAGE_HANDLER(ViewHostMsg_ImeCompositionRangeChanged,
                        OnMsgImeCompositionRangeChanged)
    IPC_MESSAGE_HANDLER(ViewHostMsg_ImeCancelComposition,
                        OnMsgImeCancelComposition)
    IPC_MESSAGE_HANDLER(ViewHostMsg_DidActivateAcceleratedCompositing,
                        OnMsgDidActivateAcceleratedCompositing)
    IPC_MESSAGE_HANDLER(ViewHostMsg_LockMouse, OnMsgLockMouse)
    IPC_MESSAGE_HANDLER(ViewHostMsg_UnlockMouse, OnMsgUnlockMouse)
#if defined(OS_POSIX) || defined(USE_AURA)
    IPC_MESSAGE_HANDLER(ViewHostMsg_GetWindowRect, OnMsgGetWindowRect)
    IPC_MESSAGE_HANDLER(ViewHostMsg_GetRootWindowRect, OnMsgGetRootWindowRect)
#endif
#if defined(OS_MACOSX)
    IPC_MESSAGE_HANDLER(ViewHostMsg_PluginFocusChanged,
                        OnMsgPluginFocusChanged)
    IPC_MESSAGE_HANDLER(ViewHostMsg_StartPluginIme,
                        OnMsgStartPluginIme)
    IPC_MESSAGE_HANDLER(ViewHostMsg_AllocateFakePluginWindowHandle,
                        OnAllocateFakePluginWindowHandle)
    IPC_MESSAGE_HANDLER(ViewHostMsg_DestroyFakePluginWindowHandle,
                        OnDestroyFakePluginWindowHandle)
    IPC_MESSAGE_HANDLER(ViewHostMsg_AcceleratedSurfaceSetIOSurface,
                        OnAcceleratedSurfaceSetIOSurface)
    IPC_MESSAGE_HANDLER(ViewHostMsg_AcceleratedSurfaceSetTransportDIB,
                        OnAcceleratedSurfaceSetTransportDIB)
    IPC_MESSAGE_HANDLER(ViewHostMsg_AcceleratedSurfaceBuffersSwapped,
                        OnAcceleratedSurfaceBuffersSwapped)
#endif
#if defined(TOOLKIT_GTK)
    IPC_MESSAGE_HANDLER(ViewHostMsg_CreatePluginContainer,
                        OnMsgCreatePluginContainer)
    IPC_MESSAGE_HANDLER(ViewHostMsg_DestroyPluginContainer,
                        OnMsgDestroyPluginContainer)
#endif
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP_EX()

  if (!msg_is_ok) {
    // The message de-serialization failed. Kill the renderer process.
    RecordAction(UserMetricsAction("BadMessageTerminate_RWH"));
    GetProcess()->ReceivedBadMessage();
  }
  return handled;
}

bool RenderWidgetHostImpl::Send(IPC::Message* msg) {
  return process_->Send(msg);
}

void RenderWidgetHostImpl::WasHidden() {
  is_hidden_ = true;

  // Don't bother reporting hung state when we aren't active.
  StopHangMonitorTimeout();

  // If we have a renderer, then inform it that we are being hidden so it can
  // reduce its resource utilization.
  Send(new ViewMsg_WasHidden(routing_id_));

  // Tell the RenderProcessHost we were hidden.
  process_->WidgetHidden();

  bool is_visible = false;
  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
      Source<RenderWidgetHost>(this),
      Details<bool>(&is_visible));
}

void RenderWidgetHostImpl::WasRestored() {
  // When we create the widget, it is created as *not* hidden.
  if (!is_hidden_)
    return;
  is_hidden_ = false;

  BackingStore* backing_store = BackingStoreManager::Lookup(this);
  // If we already have a backing store for this widget, then we don't need to
  // repaint on restore _unless_ we know that our backing store is invalid.
  // When accelerated compositing is on, we must always repaint, even when
  // the backing store exists.
  bool needs_repainting;
  if (needs_repainting_on_restore_ || !backing_store ||
      is_accelerated_compositing_active()) {
    needs_repainting = true;
    needs_repainting_on_restore_ = false;
  } else {
    needs_repainting = false;
  }
  Send(new ViewMsg_WasRestored(routing_id_, needs_repainting));

  process_->WidgetRestored();

  bool is_visible = true;
  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
      Source<RenderWidgetHost>(this),
      Details<bool>(&is_visible));

  // It's possible for our size to be out of sync with the renderer. The
  // following is one case that leads to this:
  // 1. WasResized -> Send ViewMsg_Resize to render
  // 2. WasResized -> do nothing as resize_ack_pending_ is true
  // 3. WasHidden
  // 4. OnMsgUpdateRect from (1) processed. Does NOT invoke WasResized as view
  //    is hidden. Now renderer/browser out of sync with what they think size
  //    is.
  // By invoking WasResized the renderer is updated as necessary. WasResized
  // does nothing if the sizes are already in sync.
  //
  // TODO: ideally ViewMsg_WasRestored would take a size. This way, the renderer
  // could handle both the restore and resize at once. This isn't that big a
  // deal as RenderWidget::WasRestored delays updating, so that the resize from
  // WasResized is usually processed before the renderer is painted.
  WasResized();
}

void RenderWidgetHostImpl::WasResized() {
  if (resize_ack_pending_ || !process_->HasConnection() || !view_ ||
      !renderer_initialized_ || should_auto_resize_) {
    return;
  }

#if !defined(OS_MACOSX)
  gfx::Rect view_bounds = view_->GetViewBounds();
#else
  // When UI scaling is enabled on OS X, allocate a smaller bitmap and
  // pixel-scale it up.
  // TODO(thakis): Use pixel size on mac and set UI scale in renderer.
  // http://crbug.com/31960
  gfx::Rect view_bounds(view_->GetViewCocoaBounds().size());
#endif
  gfx::Size new_size(view_bounds.size());

  bool was_fullscreen = is_fullscreen_;
  is_fullscreen_ = IsFullscreen();
  bool fullscreen_changed = was_fullscreen != is_fullscreen_;
  bool size_changed = new_size != current_size_;

  // Avoid asking the RenderWidget to resize to its current size, since it
  // won't send us a PaintRect message in that case.
  if (!size_changed && !fullscreen_changed)
    return;

  if (in_flight_size_ != gfx::Size() && new_size == in_flight_size_ &&
      !fullscreen_changed)
    return;

  // We don't expect to receive an ACK when the requested size is empty.
  if (!new_size.IsEmpty() && size_changed)
    resize_ack_pending_ = true;

  if (!Send(new ViewMsg_Resize(routing_id_, new_size,
          GetRootWindowResizerRect(), is_fullscreen_))) {
    resize_ack_pending_ = false;
  } else {
    in_flight_size_ = new_size;
  }
}

void RenderWidgetHostImpl::ResizeRectChanged(const gfx::Rect& new_rect) {
  Send(new ViewMsg_ChangeResizeRect(routing_id_, new_rect));
}

void RenderWidgetHostImpl::GotFocus() {
  Focus();
}

void RenderWidgetHostImpl::Focus() {
  Send(new ViewMsg_SetFocus(routing_id_, true));
}

void RenderWidgetHostImpl::Blur() {
  // If there is a pending mouse lock request, we don't want to reject it at
  // this point. The user can switch focus back to this view and approve the
  // request later.
  if (IsMouseLocked())
    view_->UnlockMouse();

  Send(new ViewMsg_SetFocus(routing_id_, false));
}

void RenderWidgetHostImpl::LostCapture() {
  Send(new ViewMsg_MouseCaptureLost(routing_id_));
}

void RenderWidgetHostImpl::SetActive(bool active) {
  Send(new ViewMsg_SetActive(routing_id_, active));
}

void RenderWidgetHostImpl::LostMouseLock() {
  Send(new ViewMsg_MouseLockLost(routing_id_));
}

void RenderWidgetHostImpl::ViewDestroyed() {
  RejectMouseLockOrUnlockIfNecessary();

  // TODO(evanm): tracking this may no longer be necessary;
  // eliminate this function if so.
  SetView(NULL);
}

void RenderWidgetHostImpl::SetIsLoading(bool is_loading) {
  is_loading_ = is_loading;
  if (!view_)
    return;
  view_->SetIsLoading(is_loading);
}

bool RenderWidgetHostImpl::CopyFromBackingStore(
    const gfx::Rect& src_rect,
    const gfx::Size& accelerated_dest_size,
    skia::PlatformCanvas* output) {
  if (view_ && is_accelerated_compositing_active_) {
    TRACE_EVENT0("browser",
        "RenderWidgetHostImpl::CopyFromBackingStore::FromCompositingSurface");
    // TODO(mazda): Support partial copy with |src_rect|
    // (http://crbug.com/118571).
    return view_->CopyFromCompositingSurface(accelerated_dest_size, output);
  }

  BackingStore* backing_store = GetBackingStore(false);
  if (!backing_store)
    return false;

  TRACE_EVENT0("browser",
      "RenderWidgetHostImpl::CopyFromBackingStore::FromBackingStore");
  const gfx::Size backing_store_size = backing_store->size();
  gfx::Rect copy_rect = src_rect.IsEmpty() ?
      gfx::Rect(0, 0, backing_store_size.width(), backing_store_size.height()) :
      src_rect;
  // When the result size is equal to the backing store size, copy from the
  // backing store directly to the output canvas.
  return backing_store->CopyFromBackingStore(copy_rect, output);
}

void RenderWidgetHostImpl::AsyncCopyFromBackingStore(
    const gfx::Rect& src_rect,
    const gfx::Size& accelerated_dest_size,
    skia::PlatformCanvas* output,
    base::Callback<void(bool)> callback) {
  if (view_ && is_accelerated_compositing_active_) {
    TRACE_EVENT0("browser",
        "RenderWidgetHostImpl::CopyFromBackingStore::FromCompositingSurface");
    // TODO(mazda): Support partial copy with |src_rect|
    // (http://crbug.com/118571).
    view_->AsyncCopyFromCompositingSurface(accelerated_dest_size,
                                           output,
                                           callback);
    return;
  }

  BackingStore* backing_store = GetBackingStore(false);
  if (!backing_store) {
    callback.Run(false);
    return;
  }

  TRACE_EVENT0("browser",
      "RenderWidgetHostImpl::CopyFromBackingStore::FromBackingStore");
  const gfx::Size backing_store_size = backing_store->size();
  gfx::Rect copy_rect = src_rect.IsEmpty() ?
      gfx::Rect(0, 0, backing_store_size.width(), backing_store_size.height()) :
      src_rect;
  // When the result size is equal to the backing store size, copy from the
  // backing store directly to the output canvas.
  bool result = backing_store->CopyFromBackingStore(copy_rect, output);
  callback.Run(result);
}

#if defined(TOOLKIT_GTK)
bool RenderWidgetHostImpl::CopyFromBackingStoreToGtkWindow(
    const gfx::Rect& dest_rect, GdkWindow* target) {
  BackingStore* backing_store = GetBackingStore(false);
  if (!backing_store)
    return false;
  (static_cast<BackingStoreGtk*>(backing_store))->PaintToRect(
      dest_rect, target);
  return true;
}
#elif defined(OS_MACOSX)
gfx::Size RenderWidgetHostImpl::GetBackingStoreSize() {
  BackingStore* backing_store = GetBackingStore(false);
  return backing_store ? backing_store->size() : gfx::Size();
}

bool RenderWidgetHostImpl::CopyFromBackingStoreToCGContext(
    const CGRect& dest_rect, CGContextRef target) {
  BackingStore* backing_store = GetBackingStore(false);
  if (!backing_store)
    return false;
  (static_cast<BackingStoreMac*>(backing_store))->
      CopyFromBackingStoreToCGContext(dest_rect, target);
  return true;
}
#endif

void RenderWidgetHostImpl::PaintAtSize(TransportDIB::Handle dib_handle,
                                       int tag,
                                       const gfx::Size& page_size,
                                       const gfx::Size& desired_size) {
  // Ask the renderer to create a bitmap regardless of whether it's
  // hidden, being resized, redrawn, etc.  It resizes the web widget
  // to the page_size and then scales it to the desired_size.
  Send(new ViewMsg_PaintAtSize(routing_id_, dib_handle, tag,
                               page_size, desired_size));
}

BackingStore* RenderWidgetHostImpl::GetBackingStore(bool force_create) {
  TRACE_EVENT2("renderer_host", "RenderWidgetHostImpl::GetBackingStore",
               "width", base::IntToString(current_size_.width()),
               "height", base::IntToString(current_size_.height()));

  // We should not be asked to paint while we are hidden.  If we are hidden,
  // then it means that our consumer failed to call WasRestored. If we're not
  // force creating the backing store, it's OK since we can feel free to give
  // out our cached one if we have it.
  DCHECK(!is_hidden_ || !force_create) <<
      "GetBackingStore called while hidden!";

  // We should never be called recursively; this can theoretically lead to
  // infinite recursion and almost certainly leads to lower performance.
  DCHECK(!in_get_backing_store_) << "GetBackingStore called recursively!";
  AutoReset<bool> auto_reset_in_get_backing_store(&in_get_backing_store_, true);

  // We might have a cached backing store that we can reuse!
  BackingStore* backing_store =
      BackingStoreManager::GetBackingStore(this, current_size_);
  if (!force_create)
    return backing_store;

  // If we fail to find a backing store in the cache, send out a request
  // to the renderer to paint the view if required.
  if (!backing_store && !repaint_ack_pending_ && !resize_ack_pending_ &&
      !view_being_painted_) {
    repaint_start_time_ = TimeTicks::Now();
    repaint_ack_pending_ = true;
    Send(new ViewMsg_Repaint(routing_id_, current_size_));
  }

  // When we have asked the RenderWidget to resize, and we are still waiting on
  // a response, block for a little while to see if we can't get a response
  // before returning the old (incorrectly sized) backing store.
  if (resize_ack_pending_ || !backing_store) {
    IPC::Message msg;
    TimeDelta max_delay = TimeDelta::FromMilliseconds(kPaintMsgTimeoutMS);
    if (process_->WaitForUpdateMsg(routing_id_, max_delay, &msg)) {
      OnMessageReceived(msg);
      backing_store = BackingStoreManager::GetBackingStore(this, current_size_);
    }
  }

  return backing_store;
}

BackingStore* RenderWidgetHostImpl::AllocBackingStore(const gfx::Size& size) {
  if (!view_)
    return NULL;
  return view_->AllocBackingStore(size);
}

void RenderWidgetHostImpl::DonePaintingToBackingStore() {
  Send(new ViewMsg_UpdateRect_ACK(GetRoutingID()));
}

void RenderWidgetHostImpl::ScheduleComposite() {
  if (is_hidden_ || !is_accelerated_compositing_active_) {
      return;
  }

  // Send out a request to the renderer to paint the view if required.
  if (!repaint_ack_pending_ && !resize_ack_pending_ && !view_being_painted_) {
    repaint_start_time_ = TimeTicks::Now();
    repaint_ack_pending_ = true;
    Send(new ViewMsg_Repaint(routing_id_, current_size_));
  }
}

void RenderWidgetHostImpl::StartHangMonitorTimeout(TimeDelta delay) {
  if (CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kDisableHangMonitor)) {
    return;
  }

  // Set time_when_considered_hung_ if it's null. Otherwise, update
  // time_when_considered_hung_ if the caller's request is sooner than the
  // existing one. This will have the side effect that the existing timeout will
  // be forgotten.
  Time requested_end_time = Time::Now() + delay;
  if (time_when_considered_hung_.is_null() ||
      time_when_considered_hung_ > requested_end_time)
    time_when_considered_hung_ = requested_end_time;

  // If we already have a timer with the same or shorter duration, then we can
  // wait for it to finish.
  if (hung_renderer_timer_.IsRunning() &&
      hung_renderer_timer_.GetCurrentDelay() <= delay) {
    // If time_when_considered_hung_ was null, this timer may fire early.
    // CheckRendererIsUnresponsive handles that by calling
    // StartHangMonitorTimeout with the remaining time.
    // If time_when_considered_hung_ was non-null, it means we still haven't
    // heard from the renderer so we leave time_when_considered_hung_ as is.
    return;
  }

  // Either the timer is not yet running, or we need to adjust the timer to
  // fire sooner.
  time_when_considered_hung_ = requested_end_time;
  hung_renderer_timer_.Stop();
  hung_renderer_timer_.Start(FROM_HERE, delay, this,
      &RenderWidgetHostImpl::CheckRendererIsUnresponsive);
}

void RenderWidgetHostImpl::RestartHangMonitorTimeout() {
  // Setting to null will cause StartHangMonitorTimeout to restart the timer.
  time_when_considered_hung_ = Time();
  StartHangMonitorTimeout(
      TimeDelta::FromMilliseconds(hung_renderer_delay_ms_));
}

void RenderWidgetHostImpl::StopHangMonitorTimeout() {
  time_when_considered_hung_ = Time();
  RendererIsResponsive();
  // We do not bother to stop the hung_renderer_timer_ here in case it will be
  // started again shortly, which happens to be the common use case.
}

void RenderWidgetHostImpl::EnableFullAccessibilityMode() {
  SetAccessibilityMode(AccessibilityModeComplete);
}

void RenderWidgetHostImpl::ForwardMouseEvent(const WebMouseEvent& mouse_event) {
  TRACE_EVENT2("renderer_host", "RenderWidgetHostImpl::ForwardMouseEvent",
               "x", mouse_event.x, "y", mouse_event.y);
  if (ignore_input_events_ || process_->IgnoreInputEvents())
    return;

  // Avoid spamming the renderer with mouse move events.  It is important
  // to note that WM_MOUSEMOVE events are anyways synthetic, but since our
  // thread is able to rapidly consume WM_MOUSEMOVE events, we may get way
  // more WM_MOUSEMOVE events than we wish to send to the renderer.
  if (mouse_event.type == WebInputEvent::MouseMove) {
    if (mouse_move_pending_) {
      if (!next_mouse_move_.get()) {
        next_mouse_move_.reset(new WebMouseEvent(mouse_event));
      } else {
        // Accumulate movement deltas.
        int x = next_mouse_move_->movementX;
        int y = next_mouse_move_->movementY;
        *next_mouse_move_ = mouse_event;
        next_mouse_move_->movementX += x;
        next_mouse_move_->movementY += y;
      }
      return;
    }
    mouse_move_pending_ = true;
  } else if (mouse_event.type == WebInputEvent::MouseDown) {
    if (tap_suppression_controller_->ShouldDeferMouseDown(mouse_event))
      return;
    OnUserGesture();
  } else if (mouse_event.type == WebInputEvent::MouseUp) {
    if (tap_suppression_controller_->ShouldSuppressMouseUp())
      return;
  }

  ForwardInputEvent(mouse_event, sizeof(WebMouseEvent), false);
}

void RenderWidgetHostImpl::OnMouseActivate() {
}

void RenderWidgetHostImpl::ForwardWheelEvent(
    const WebMouseWheelEvent& wheel_event) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardWheelEvent");
  if (ignore_input_events_ || process_->IgnoreInputEvents())
    return;

  // If there's already a mouse wheel event waiting to be sent to the renderer,
  // add the new deltas to that event. Not doing so (e.g., by dropping the old
  // event, as for mouse moves) results in very slow scrolling on the Mac (on
  // which many, very small wheel events are sent).
  if (mouse_wheel_pending_) {
    if (coalesced_mouse_wheel_events_.empty() ||
        !ShouldCoalesceMouseWheelEvents(coalesced_mouse_wheel_events_.back(),
                                        wheel_event)) {
      coalesced_mouse_wheel_events_.push_back(wheel_event);
    } else {
      WebMouseWheelEvent* last_wheel_event =
          &coalesced_mouse_wheel_events_.back();
      last_wheel_event->deltaX += wheel_event.deltaX;
      last_wheel_event->deltaY += wheel_event.deltaY;
      last_wheel_event->wheelTicksX += wheel_event.wheelTicksX;
      last_wheel_event->wheelTicksY += wheel_event.wheelTicksY;
      DCHECK_GE(wheel_event.timeStampSeconds,
                last_wheel_event->timeStampSeconds);
      last_wheel_event->timeStampSeconds = wheel_event.timeStampSeconds;
    }
    return;
  }
  mouse_wheel_pending_ = true;
  current_wheel_event_ = wheel_event;

  HISTOGRAM_COUNTS_100("MPArch.RWH_WheelQueueSize",
                       coalesced_mouse_wheel_events_.size());

  ForwardInputEvent(wheel_event, sizeof(WebMouseWheelEvent), false);
}

void RenderWidgetHostImpl::ForwardGestureEvent(
    const WebKit::WebGestureEvent& gesture_event) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardGestureEvent");
  if (ignore_input_events_ || process_->IgnoreInputEvents())
    return;

  if (gesture_event.type == WebInputEvent::GestureFlingCancel)
    tap_suppression_controller_->GestureFlingCancel(
        gesture_event.timeStampSeconds);
  ForwardInputEvent(gesture_event, sizeof(WebGestureEvent), false);
}

void RenderWidgetHostImpl::ForwardKeyboardEvent(
    const NativeWebKeyboardEvent& key_event) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardKeyboardEvent");
  if (ignore_input_events_ || process_->IgnoreInputEvents())
    return;

  if (key_event.type == WebKeyboardEvent::Char &&
      (key_event.windowsKeyCode == ui::VKEY_RETURN ||
       key_event.windowsKeyCode == ui::VKEY_SPACE)) {
    OnUserGesture();
  }

  // Double check the type to make sure caller hasn't sent us nonsense that
  // will mess up our key queue.
  if (WebInputEvent::isKeyboardEventType(key_event.type)) {
    if (suppress_next_char_events_) {
      // If preceding RawKeyDown event was handled by the browser, then we need
      // suppress all Char events generated by it. Please note that, one
      // RawKeyDown event may generate multiple Char events, so we can't reset
      // |suppress_next_char_events_| until we get a KeyUp or a RawKeyDown.
      if (key_event.type == WebKeyboardEvent::Char)
        return;
      // We get a KeyUp or a RawKeyDown event.
      suppress_next_char_events_ = false;
    }

    bool is_keyboard_shortcut = false;
    // Only pre-handle the key event if it's not handled by the input method.
    if (!key_event.skip_in_browser) {
      // We need to set |suppress_next_char_events_| to true if
      // PreHandleKeyboardEvent() returns true, but |this| may already be
      // destroyed at that time. So set |suppress_next_char_events_| true here,
      // then revert it afterwards when necessary.
      if (key_event.type == WebKeyboardEvent::RawKeyDown)
        suppress_next_char_events_ = true;

      // Tab switching/closing accelerators aren't sent to the renderer to avoid
      // a hung/malicious renderer from interfering.
      if (PreHandleKeyboardEvent(key_event, &is_keyboard_shortcut))
        return;

      if (key_event.type == WebKeyboardEvent::RawKeyDown)
        suppress_next_char_events_ = false;
    }

    // Don't add this key to the queue if we have no way to send the message...
    if (!process_->HasConnection())
      return;

    // Put all WebKeyboardEvent objects in a queue since we can't trust the
    // renderer and we need to give something to the UnhandledInputEvent
    // handler.
    key_queue_.push_back(key_event);
    HISTOGRAM_COUNTS_100("Renderer.KeyboardQueueSize", key_queue_.size());

    // Only forward the non-native portions of our event.
    ForwardInputEvent(key_event, sizeof(WebKeyboardEvent),
                      is_keyboard_shortcut);
  }
}

void RenderWidgetHostImpl::ForwardInputEvent(const WebInputEvent& input_event,
                                             int event_size,
                                             bool is_keyboard_shortcut) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardInputEvent");

  if (!process_->HasConnection())
    return;

  DCHECK(!process_->IgnoreInputEvents());

  IPC::Message* message = new ViewMsg_HandleInputEvent(routing_id_);
  message->WriteData(
      reinterpret_cast<const char*>(&input_event), event_size);
  // |is_keyboard_shortcut| only makes sense for RawKeyDown events.
  if (input_event.type == WebInputEvent::RawKeyDown)
    message->WriteBool(is_keyboard_shortcut);
  input_event_start_time_ = TimeTicks::Now();
  Send(message);

  // Any non-wheel input event cancels pending wheel events.
  if (input_event.type != WebInputEvent::MouseWheel)
    coalesced_mouse_wheel_events_.clear();

  // Any input event cancels a pending mouse move event. Note that
  // |next_mouse_move_| possibly owns |input_event|, so don't use |input_event|
  // after this line.
  next_mouse_move_.reset();

  increment_in_flight_event_count();
  StartHangMonitorTimeout(
      TimeDelta::FromMilliseconds(hung_renderer_delay_ms_));
}

void RenderWidgetHostImpl::ForwardTouchEvent(
    const WebKit::WebTouchEvent& touch_event) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardTouchEvent");
  if (ignore_input_events_ || process_->IgnoreInputEvents())
    return;

  // TODO(sad): Do touch-event coalescing when appropriate.
  ForwardInputEvent(touch_event, sizeof(WebKit::WebTouchEvent), false);
}

#if defined(TOOLKIT_GTK)
bool RenderWidgetHostImpl::KeyPressListenersHandleEvent(GdkEventKey* event) {
  if (event->type != GDK_KEY_PRESS)
    return false;

  for (std::list<KeyboardListener*>::iterator it = keyboard_listeners_.begin();
       it != keyboard_listeners_.end(); ++it) {
    if ((*it)->HandleKeyPressEvent(event))
      return true;
  }

  return false;
}
#endif  // defined(TOOLKIT_GTK)

void RenderWidgetHostImpl::AddKeyboardListener(KeyboardListener* listener) {
  keyboard_listeners_.push_back(listener);
}

void RenderWidgetHostImpl::RemoveKeyboardListener(
    KeyboardListener* listener) {
  keyboard_listeners_.remove(listener);
}

void RenderWidgetHostImpl::RendererExited(base::TerminationStatus status,
                                          int exit_code) {
  // Clearing this flag causes us to re-create the renderer when recovering
  // from a crashed renderer.
  renderer_initialized_ = false;

  // Must reset these to ensure that mouse move/wheel events work with a new
  // renderer.
  mouse_move_pending_ = false;
  next_mouse_move_.reset();
  mouse_wheel_pending_ = false;
  coalesced_mouse_wheel_events_.clear();

  // Must reset these to ensure that keyboard events work with a new renderer.
  key_queue_.clear();
  suppress_next_char_events_ = false;

  // Reset some fields in preparation for recovering from a crash.
  resize_ack_pending_ = false;
  repaint_ack_pending_ = false;

  in_flight_size_.SetSize(0, 0);
  current_size_.SetSize(0, 0);
  is_hidden_ = false;
  is_accelerated_compositing_active_ = false;

  // Reset this to ensure the hung renderer mechanism is working properly.
  in_flight_event_count_ = 0;

  if (view_) {
    GpuSurfaceTracker::Get()->SetSurfaceHandle(surface_id_,
                                               gfx::GLSurfaceHandle());
    view_->RenderViewGone(status, exit_code);
    view_ = NULL;  // The View should be deleted by RenderViewGone.
  }

  BackingStoreManager::RemoveBackingStore(this);
}

void RenderWidgetHostImpl::UpdateTextDirection(WebTextDirection direction) {
  text_direction_updated_ = true;
  text_direction_ = direction;
}

void RenderWidgetHostImpl::CancelUpdateTextDirection() {
  if (text_direction_updated_)
    text_direction_canceled_ = true;
}

void RenderWidgetHostImpl::NotifyTextDirection() {
  if (text_direction_updated_) {
    if (!text_direction_canceled_)
      Send(new ViewMsg_SetTextDirection(GetRoutingID(), text_direction_));
    text_direction_updated_ = false;
    text_direction_canceled_ = false;
  }
}

void RenderWidgetHostImpl::SetInputMethodActive(bool activate) {
  Send(new ViewMsg_SetInputMethodActive(GetRoutingID(), activate));
}

void RenderWidgetHostImpl::ImeSetComposition(
    const string16& text,
    const std::vector<WebKit::WebCompositionUnderline>& underlines,
    int selection_start,
    int selection_end) {
  Send(new ViewMsg_ImeSetComposition(
            GetRoutingID(), text, underlines, selection_start, selection_end));
}

void RenderWidgetHostImpl::ImeConfirmComposition(const string16& text) {
  ImeConfirmComposition(text, ui::Range::InvalidRange());
}

void RenderWidgetHostImpl::ImeConfirmComposition(
    const string16& text, const ui::Range& replacement_range) {
  Send(new ViewMsg_ImeConfirmComposition(
        GetRoutingID(), text, replacement_range));
}

void RenderWidgetHostImpl::ImeConfirmComposition() {
  ImeConfirmComposition(string16());
}

void RenderWidgetHostImpl::ImeCancelComposition() {
  Send(new ViewMsg_ImeSetComposition(GetRoutingID(), string16(),
            std::vector<WebKit::WebCompositionUnderline>(), 0, 0));
}

gfx::Rect RenderWidgetHostImpl::GetRootWindowResizerRect() const {
  return gfx::Rect();
}

void RenderWidgetHostImpl::RequestToLockMouse() {
  // Directly reject to lock the mouse. Subclass can override this method to
  // decide whether to allow mouse lock or not.
  GotResponseToLockMouseRequest(false);
}

void RenderWidgetHostImpl::RejectMouseLockOrUnlockIfNecessary() {
  DCHECK(!pending_mouse_lock_request_ || !IsMouseLocked());
  if (pending_mouse_lock_request_) {
    pending_mouse_lock_request_ = false;
    Send(new ViewMsg_LockMouse_ACK(routing_id_, false));
  } else if (IsMouseLocked()) {
    view_->UnlockMouse();
  }
}

bool RenderWidgetHostImpl::IsMouseLocked() const {
  return view_ ? view_->IsMouseLocked() : false;
}

bool RenderWidgetHostImpl::IsFullscreen() const {
  return false;
}

void RenderWidgetHostImpl::SetShouldAutoResize(bool enable) {
  should_auto_resize_ = enable;
}

void RenderWidgetHostImpl::Destroy() {
  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_HOST_DESTROYED,
      Source<RenderWidgetHost>(this),
      NotificationService::NoDetails());

  // Tell the view to die.
  // Note that in the process of the view shutting down, it can call a ton
  // of other messages on us.  So if you do any other deinitialization here,
  // do it after this call to view_->Destroy().
  if (view_)
    view_->Destroy();

  delete this;
}

void RenderWidgetHostImpl::CheckRendererIsUnresponsive() {
  // If we received a call to StopHangMonitorTimeout.
  if (time_when_considered_hung_.is_null())
    return;

  // If we have not waited long enough, then wait some more.
  Time now = Time::Now();
  if (now < time_when_considered_hung_) {
    StartHangMonitorTimeout(time_when_considered_hung_ - now);
    return;
  }

  // OK, looks like we have a hung renderer!
  NotificationService::current()->Notify(
      NOTIFICATION_RENDERER_PROCESS_HANG,
      Source<RenderWidgetHost>(this),
      NotificationService::NoDetails());
  is_unresponsive_ = true;
  NotifyRendererUnresponsive();
}

void RenderWidgetHostImpl::RendererIsResponsive() {
  if (is_unresponsive_) {
    is_unresponsive_ = false;
    NotifyRendererResponsive();
  }
}

void RenderWidgetHostImpl::OnMsgRenderViewReady() {
  WasResized();
}

void RenderWidgetHostImpl::OnMsgRenderViewGone(int status, int exit_code) {
  // TODO(evanm): This synchronously ends up calling "delete this".
  // Is that really what we want in response to this message?  I'm matching
  // previous behavior of the code here.
  Destroy();
}

void RenderWidgetHostImpl::OnMsgClose() {
  Shutdown();
}

void RenderWidgetHostImpl::OnMsgSetTooltipText(
    const string16& tooltip_text,
    WebTextDirection text_direction_hint) {
  // First, add directionality marks around tooltip text if necessary.
  // A naive solution would be to simply always wrap the text. However, on
  // windows, Unicode directional embedding characters can't be displayed on
  // systems that lack RTL fonts and are instead displayed as empty squares.
  //
  // To get around this we only wrap the string when we deem it necessary i.e.
  // when the locale direction is different than the tooltip direction hint.
  //
  // Currently, we use element's directionality as the tooltip direction hint.
  // An alternate solution would be to set the overall directionality based on
  // trying to detect the directionality from the tooltip text rather than the
  // element direction.  One could argue that would be a preferable solution
  // but we use the current approach to match Fx & IE's behavior.
  string16 wrapped_tooltip_text = tooltip_text;
  if (!tooltip_text.empty()) {
    if (text_direction_hint == WebKit::WebTextDirectionLeftToRight) {
      // Force the tooltip to have LTR directionality.
      wrapped_tooltip_text =
          base::i18n::GetDisplayStringInLTRDirectionality(wrapped_tooltip_text);
    } else if (text_direction_hint == WebKit::WebTextDirectionRightToLeft &&
               !base::i18n::IsRTL()) {
      // Force the tooltip to have RTL directionality.
      base::i18n::WrapStringWithRTLFormatting(&wrapped_tooltip_text);
    }
  }
  if (GetView())
    view_->SetTooltipText(wrapped_tooltip_text);
}

void RenderWidgetHostImpl::OnMsgRequestMove(const gfx::Rect& pos) {
  // Note that we ignore the position.
  if (view_) {
    view_->SetBounds(pos);
    Send(new ViewMsg_Move_ACK(routing_id_));
  }
}

void RenderWidgetHostImpl::OnMsgPaintAtSizeAck(int tag, const gfx::Size& size) {
  std::pair<int, gfx::Size> details = std::make_pair(tag, size);
  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_HOST_DID_RECEIVE_PAINT_AT_SIZE_ACK,
      Source<RenderWidgetHost>(this),
      Details<std::pair<int, gfx::Size> >(&details));
}

void RenderWidgetHostImpl::OnMsgUpdateRect(
    const ViewHostMsg_UpdateRect_Params& params) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::OnMsgUpdateRect");
  TimeTicks paint_start = TimeTicks::Now();

  // Update our knowledge of the RenderWidget's size.
  current_size_ = params.view_size;
  // Update our knowledge of the RenderWidget's scroll offset.
  last_scroll_offset_ = params.scroll_offset;

  bool is_resize_ack =
      ViewHostMsg_UpdateRect_Flags::is_resize_ack(params.flags);

  // resize_ack_pending_ needs to be cleared before we call DidPaintRect, since
  // that will end up reaching GetBackingStore.
  if (is_resize_ack) {
    DCHECK(resize_ack_pending_);
    resize_ack_pending_ = false;
    in_flight_size_.SetSize(0, 0);
  }

  bool is_repaint_ack =
      ViewHostMsg_UpdateRect_Flags::is_repaint_ack(params.flags);
  if (is_repaint_ack) {
    repaint_ack_pending_ = false;
    TimeDelta delta = TimeTicks::Now() - repaint_start_time_;
    UMA_HISTOGRAM_TIMES("MPArch.RWH_RepaintDelta", delta);
  }

  DCHECK(!params.view_size.IsEmpty());

  bool was_async = false;
  if (!is_accelerated_compositing_active_) {
    DCHECK(!params.bitmap_rect.IsEmpty());
    const size_t size = params.bitmap_rect.height() *
        params.bitmap_rect.width() * 4;
    TransportDIB* dib = process_->GetTransportDIB(params.bitmap);

    // If gpu process does painting, scroll_rect and copy_rects are always empty
    // and backing store is never used.
    if (dib) {
      if (dib->size() < size) {
        DLOG(WARNING) << "Transport DIB too small for given rectangle";
        RecordAction(UserMetricsAction("BadMessageTerminate_RWH1"));
        GetProcess()->ReceivedBadMessage();
      } else {
        UNSHIPPED_TRACE_EVENT_INSTANT2("test_latency", "UpdateRect",
            "x+y", params.bitmap_rect.x() + params.bitmap_rect.y(),
            "color", 0xffffff & *static_cast<uint32*>(dib->memory()));
        UNSHIPPED_TRACE_EVENT_INSTANT1("test_latency", "UpdateRectWidth",
            "width", params.bitmap_rect.width());

        // Scroll the backing store.
        if (!params.scroll_rect.IsEmpty()) {
          ScrollBackingStoreRect(params.dx, params.dy,
                                 params.scroll_rect,
                                 params.view_size);
        }

        // Paint the backing store. This will update it with the
        // renderer-supplied bits. The view will read out of the backing store
        // later to actually draw to the screen.
        was_async = PaintBackingStoreRect(
            params.bitmap,
            params.bitmap_rect,
            params.copy_rects,
            params.view_size,
            base::Bind(&RenderWidgetHostImpl::DidUpdateBackingStore,
                       weak_factory_.GetWeakPtr(), params, paint_start));
      }
    }
  }

  if (!was_async) {
    DidUpdateBackingStore(params, paint_start);
  }

  if (should_auto_resize_) {
    bool post_callback = new_auto_size_.IsEmpty();
    new_auto_size_ = params.view_size;
    if (post_callback) {
      MessageLoop::current()->PostTask(
          FROM_HERE,
          base::Bind(&RenderWidgetHostImpl::DelayedAutoResized,
                     weak_factory_.GetWeakPtr()));
    }
  }

  // Log the time delta for processing a paint message. On platforms that don't
  // support asynchronous painting, this is equivalent to
  // MPArch.RWH_TotalPaintTime.
  TimeDelta delta = TimeTicks::Now() - paint_start;
  UMA_HISTOGRAM_TIMES("MPArch.RWH_OnMsgUpdateRect", delta);
}

void RenderWidgetHostImpl::OnMsgUpdateIsDelayed() {
  // Nothing to do, this message was just to unblock the UI thread.
}

void RenderWidgetHostImpl::DidUpdateBackingStore(
    const ViewHostMsg_UpdateRect_Params& params,
    const TimeTicks& paint_start) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::DidUpdateBackingStore");
  TimeTicks update_start = TimeTicks::Now();

  if (params.needs_ack) {
    // ACK early so we can prefetch the next PaintRect if there is a next one.
    // This must be done AFTER we're done painting with the bitmap supplied by
    // the renderer. This ACK is a signal to the renderer that the backing store
    // can be re-used, so the bitmap may be invalid after this call.
    Send(new ViewMsg_UpdateRect_ACK(routing_id_));
  }

  // Move the plugins if the view hasn't already been destroyed.  Plugin moves
  // will not be re-issued, so must move them now, regardless of whether we
  // paint or not.  MovePluginWindows attempts to move the plugin windows and
  // in the process could dispatch other window messages which could cause the
  // view to be destroyed.
  if (view_)
    view_->MovePluginWindows(params.plugin_window_moves);

  // We don't need to update the view if the view is hidden. We must do this
  // early return after the ACK is sent, however, or the renderer will not send
  // us more data.
  if (is_hidden_)
    return;

  // Now paint the view. Watch out: it might be destroyed already.
  if (view_ && !is_accelerated_compositing_active_) {
    view_being_painted_ = true;
    view_->DidUpdateBackingStore(params.scroll_rect, params.dx, params.dy,
                                 params.copy_rects);
    view_being_painted_ = false;
  }

  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_HOST_DID_PAINT,
      Source<RenderWidgetHost>(this),
      NotificationService::NoDetails());

  // If we got a resize ack, then perhaps we have another resize to send?
  bool is_resize_ack =
      ViewHostMsg_UpdateRect_Flags::is_resize_ack(params.flags);
  if (is_resize_ack && view_) {
    gfx::Rect view_bounds = view_->GetViewBounds();
    if (current_size_ != view_bounds.size())
      WasResized();
  }

  // Log the time delta for processing a paint message.
  TimeTicks now = TimeTicks::Now();
  TimeDelta delta = now - update_start;
  UMA_HISTOGRAM_TIMES("MPArch.RWH_DidUpdateBackingStore", delta);

  // Measures the time from receiving the MsgUpdateRect IPC to completing the
  // DidUpdateBackingStore() method.  On platforms which have asynchronous
  // painting, such as Linux, this is the sum of MPArch.RWH_OnMsgUpdateRect,
  // MPArch.RWH_DidUpdateBackingStore, and the time spent asynchronously
  // waiting for the paint to complete.
  //
  // On other platforms, this will be equivalent to MPArch.RWH_OnMsgUpdateRect.
  delta = now - paint_start;
  UMA_HISTOGRAM_TIMES("MPArch.RWH_TotalPaintTime", delta);
}

void RenderWidgetHostImpl::OnMsgInputEventAck(WebInputEvent::Type event_type,
                                              bool processed) {
  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::OnMsgInputEventAck");

  // Log the time delta for processing an input event.
  TimeDelta delta = TimeTicks::Now() - input_event_start_time_;
  UMA_HISTOGRAM_TIMES("MPArch.RWH_InputEventDelta", delta);

  // Cancel pending hung renderer checks since the renderer is responsive.
  if (decrement_in_flight_event_count() == 0)
    StopHangMonitorTimeout();

  int type = static_cast<int>(event_type);
  if (type < WebInputEvent::Undefined) {
    RecordAction(UserMetricsAction("BadMessageTerminate_RWH2"));
    process_->ReceivedBadMessage();
  } else if (type == WebInputEvent::MouseMove) {
    mouse_move_pending_ = false;

    // now, we can send the next mouse move event
    if (next_mouse_move_.get()) {
      DCHECK(next_mouse_move_->type == WebInputEvent::MouseMove);
      ForwardMouseEvent(*next_mouse_move_);
    }
  } else if (WebInputEvent::isKeyboardEventType(type)) {
    ProcessKeyboardEventAck(type, processed);
  } else if (type == WebInputEvent::MouseWheel) {
    ProcessWheelAck(processed);
  } else if (WebInputEvent::isTouchEventType(type)) {
    ProcessTouchAck(event_type, processed);
  } else if (type == WebInputEvent::GestureFlingCancel) {
    tap_suppression_controller_->GestureFlingCancelAck(processed);
  }

  // This is used only for testing, and the other end does not use the
  // source object.  On linux, specifying
  // Source<RenderWidgetHost> results in a very strange
  // runtime error in the epilogue of the enclosing
  // (OnMsgInputEventAck) method, but not on other platforms; using
  // 'void' instead is just as safe (since NotificationSource
  // is not actually typesafe) and avoids this error.
  NotificationService::current()->Notify(
      NOTIFICATION_RENDER_WIDGET_HOST_DID_RECEIVE_INPUT_EVENT_ACK,
      Source<void>(this),
      Details<int>(&type));
}

void RenderWidgetHostImpl::ProcessWheelAck(bool processed) {
  mouse_wheel_pending_ = false;

  // Now send the next (coalesced) mouse wheel event.
  if (!coalesced_mouse_wheel_events_.empty()) {
    WebMouseWheelEvent next_wheel_event =
        coalesced_mouse_wheel_events_.front();
    coalesced_mouse_wheel_events_.pop_front();
    ForwardWheelEvent(next_wheel_event);
  }

  if (!processed && !is_hidden_ && view_)
    view_->UnhandledWheelEvent(current_wheel_event_);
}

void RenderWidgetHostImpl::ProcessTouchAck(
    WebInputEvent::Type type, bool processed) {
  if (view_)
    view_->ProcessTouchAck(type, processed);
}

void RenderWidgetHostImpl::OnMsgFocus() {
  // Only RenderViewHost can deal with that message.
  RecordAction(UserMetricsAction("BadMessageTerminate_RWH4"));
  GetProcess()->ReceivedBadMessage();
}

void RenderWidgetHostImpl::OnMsgBlur() {
  // Only RenderViewHost can deal with that message.
  RecordAction(UserMetricsAction("BadMessageTerminate_RWH5"));
  GetProcess()->ReceivedBadMessage();
}

void RenderWidgetHostImpl::OnMsgDidChangeNumTouchEvents(int count) {
  has_touch_handler_ = count > 0;
}

void RenderWidgetHostImpl::OnMsgSetCursor(const WebCursor& cursor) {
  if (!view_) {
    return;
  }
  view_->UpdateCursor(cursor);
}

void RenderWidgetHostImpl::OnMsgTextInputStateChanged(
    ui::TextInputType type,
    bool can_compose_inline) {
  if (view_)
    view_->TextInputStateChanged(type, can_compose_inline);
}

void RenderWidgetHostImpl::OnMsgImeCompositionRangeChanged(
    const ui::Range& range) {
  if (view_)
    view_->ImeCompositionRangeChanged(range);
}

void RenderWidgetHostImpl::OnMsgImeCancelComposition() {
  if (view_)
    view_->ImeCancelComposition();
}

void RenderWidgetHostImpl::OnMsgDidActivateAcceleratedCompositing(
    bool activated) {
  TRACE_EVENT1("renderer_host",
               "RenderWidgetHostImpl::OnMsgDidActivateAcceleratedCompositing",
               "activated", activated);
  is_accelerated_compositing_active_ = activated;
  if (view_)
    view_->OnAcceleratedCompositingStateChange();
}

void RenderWidgetHostImpl::OnMsgLockMouse() {
  if (pending_mouse_lock_request_) {
    Send(new ViewMsg_LockMouse_ACK(routing_id_, false));
    return;
  } else if (IsMouseLocked()) {
    Send(new ViewMsg_LockMouse_ACK(routing_id_, true));
    return;
  }

  pending_mouse_lock_request_ = true;
  RequestToLockMouse();
}

void RenderWidgetHostImpl::OnMsgUnlockMouse() {
  RejectMouseLockOrUnlockIfNecessary();
}

#if defined(OS_POSIX) || defined(USE_AURA)
void RenderWidgetHostImpl::OnMsgGetWindowRect(gfx::NativeViewId window_id,
                                              gfx::Rect* results) {
  if (view_)
    *results = view_->GetViewBounds();
}

void RenderWidgetHostImpl::OnMsgGetRootWindowRect(gfx::NativeViewId window_id,
                                              gfx::Rect* results) {
  if (view_)
    *results = view_->GetRootWindowBounds();
}
#endif

bool RenderWidgetHostImpl::PaintBackingStoreRect(
    TransportDIB::Id bitmap,
    const gfx::Rect& bitmap_rect,
    const std::vector<gfx::Rect>& copy_rects,
    const gfx::Size& view_size,
    const base::Closure& completion_callback) {
  // The view may be destroyed already.
  if (!view_)
    return false;

  if (is_hidden_) {
    // Don't bother updating the backing store when we're hidden. Just mark it
    // as being totally invalid. This will cause a complete repaint when the
    // view is restored.
    needs_repainting_on_restore_ = true;
    return false;
  }

  bool needs_full_paint = false;
  bool scheduled_completion_callback = false;
  BackingStoreManager::PrepareBackingStore(this, view_size, bitmap, bitmap_rect,
                                           copy_rects, completion_callback,
                                           &needs_full_paint,
                                           &scheduled_completion_callback);
  if (needs_full_paint) {
    repaint_start_time_ = TimeTicks::Now();
    repaint_ack_pending_ = true;
    Send(new ViewMsg_Repaint(routing_id_, view_size));
  }

  return scheduled_completion_callback;
}

void RenderWidgetHostImpl::ScrollBackingStoreRect(int dx, int dy,
                                                  const gfx::Rect& clip_rect,
                                                  const gfx::Size& view_size) {
  if (is_hidden_) {
    // Don't bother updating the backing store when we're hidden. Just mark it
    // as being totally invalid. This will cause a complete repaint when the
    // view is restored.
    needs_repainting_on_restore_ = true;
    return;
  }

  // TODO(darin): do we need to do something else if our backing store is not
  // the same size as the advertised view?  maybe we just assume there is a
  // full paint on its way?
  BackingStore* backing_store = BackingStoreManager::Lookup(this);
  if (!backing_store || (backing_store->size() != view_size))
    return;
  backing_store->ScrollBackingStore(dx, dy, clip_rect, view_size);
}

void RenderWidgetHostImpl::Replace(const string16& word) {
  Send(new ViewMsg_Replace(routing_id_, word));
}

void RenderWidgetHostImpl::SetIgnoreInputEvents(bool ignore_input_events) {
  ignore_input_events_ = ignore_input_events;
}

void RenderWidgetHostImpl::ProcessKeyboardEventAck(int type, bool processed) {
  if (key_queue_.empty()) {
    LOG(ERROR) << "Got a KeyEvent back from the renderer but we "
               << "don't seem to have sent it to the renderer!";
  } else if (key_queue_.front().type != type) {
    LOG(ERROR) << "We seem to have a different key type sent from "
               << "the renderer. (" << key_queue_.front().type << " vs. "
               << type << "). Ignoring event.";

    // Something must be wrong. Clear the |key_queue_| and
    // |suppress_next_char_events_| so that we can resume from the error.
    key_queue_.clear();
    suppress_next_char_events_ = false;
  } else {
    NativeWebKeyboardEvent front_item = key_queue_.front();
    key_queue_.pop_front();

#if defined(OS_MACOSX)
    if (!is_hidden_ && view_->PostProcessEventForPluginIme(front_item))
      return;
#endif

    // We only send unprocessed key event upwards if we are not hidden,
    // because the user has moved away from us and no longer expect any effect
    // of this key event.
    if (!processed && !is_hidden_ && !front_item.skip_in_browser) {
      UnhandledKeyboardEvent(front_item);

      // WARNING: This RenderWidgetHostImpl can be deallocated at this point
      // (i.e.  in the case of Ctrl+W, where the call to
      // UnhandledKeyboardEvent destroys this RenderWidgetHostImpl).
    }
  }
}

void RenderWidgetHostImpl::ActivateDeferredPluginHandles() {
#if !defined(USE_AURA)
  if (view_ == NULL)
    return;

  for (int i = 0; i < static_cast<int>(deferred_plugin_handles_.size()); i++) {
#if defined(TOOLKIT_GTK)
    view_->CreatePluginContainer(deferred_plugin_handles_[i]);
#endif
  }

  deferred_plugin_handles_.clear();
#endif
}

const gfx::Point& RenderWidgetHostImpl::GetLastScrollOffset() const {
  return last_scroll_offset_;
}

void RenderWidgetHostImpl::StartUserGesture() {
  OnUserGesture();
}

void RenderWidgetHostImpl::Stop() {
  Send(new ViewMsg_Stop(GetRoutingID()));
}

void RenderWidgetHostImpl::SetBackground(const SkBitmap& background) {
  Send(new ViewMsg_SetBackground(GetRoutingID(), background));
}

void RenderWidgetHostImpl::SetEditCommandsForNextKeyEvent(
    const std::vector<EditCommand>& commands) {
  Send(new ViewMsg_SetEditCommandsForNextKeyEvent(GetRoutingID(), commands));
}

void RenderWidgetHostImpl::SetAccessibilityMode(AccessibilityMode mode) {
  Send(new AccessibilityMsg_SetMode(routing_id_, mode));
}

void RenderWidgetHostImpl::AccessibilityDoDefaultAction(int object_id) {
  Send(new AccessibilityMsg_DoDefaultAction(GetRoutingID(), object_id));
}

void RenderWidgetHostImpl::AccessibilitySetFocus(int object_id) {
  Send(new AccessibilityMsg_SetFocus(GetRoutingID(), object_id));
}

void RenderWidgetHostImpl::AccessibilityScrollToMakeVisible(
    int acc_obj_id, gfx::Rect subfocus) {
  Send(new AccessibilityMsg_ScrollToMakeVisible(
      GetRoutingID(), acc_obj_id, subfocus));
}

void RenderWidgetHostImpl::AccessibilityScrollToPoint(
    int acc_obj_id, gfx::Point point) {
  Send(new AccessibilityMsg_ScrollToPoint(
      GetRoutingID(), acc_obj_id, point));
}

void RenderWidgetHostImpl::AccessibilitySetTextSelection(
    int object_id, int start_offset, int end_offset) {
  Send(new AccessibilityMsg_SetTextSelection(
      GetRoutingID(), object_id, start_offset, end_offset));
}

void RenderWidgetHostImpl::ExecuteEditCommand(const std::string& command,
                                              const std::string& value) {
  Send(new ViewMsg_ExecuteEditCommand(GetRoutingID(), command, value));
}

void RenderWidgetHostImpl::ScrollFocusedEditableNodeIntoRect(
    const gfx::Rect& rect) {
  Send(new ViewMsg_ScrollFocusedEditableNodeIntoRect(GetRoutingID(), rect));
}

void RenderWidgetHostImpl::SelectRange(const gfx::Point& start,
                                       const gfx::Point& end) {
  Send(new ViewMsg_SelectRange(GetRoutingID(), start, end));
}

void RenderWidgetHostImpl::Undo() {
  Send(new ViewMsg_Undo(GetRoutingID()));
  RecordAction(UserMetricsAction("Undo"));
}

void RenderWidgetHostImpl::Redo() {
  Send(new ViewMsg_Redo(GetRoutingID()));
  RecordAction(UserMetricsAction("Redo"));
}

void RenderWidgetHostImpl::Cut() {
  Send(new ViewMsg_Cut(GetRoutingID()));
  RecordAction(UserMetricsAction("Cut"));
}

void RenderWidgetHostImpl::Copy() {
  Send(new ViewMsg_Copy(GetRoutingID()));
  RecordAction(UserMetricsAction("Copy"));
}

void RenderWidgetHostImpl::CopyToFindPboard() {
#if defined(OS_MACOSX)
  // Windows/Linux don't have the concept of a find pasteboard.
  Send(new ViewMsg_CopyToFindPboard(GetRoutingID()));
  RecordAction(UserMetricsAction("CopyToFindPboard"));
#endif
}

void RenderWidgetHostImpl::Paste() {
  Send(new ViewMsg_Paste(GetRoutingID()));
  RecordAction(UserMetricsAction("Paste"));
}

void RenderWidgetHostImpl::PasteAndMatchStyle() {
  Send(new ViewMsg_PasteAndMatchStyle(GetRoutingID()));
  RecordAction(UserMetricsAction("PasteAndMatchStyle"));
}

void RenderWidgetHostImpl::Delete() {
  Send(new ViewMsg_Delete(GetRoutingID()));
  RecordAction(UserMetricsAction("DeleteSelection"));
}

void RenderWidgetHostImpl::SelectAll() {
  Send(new ViewMsg_SelectAll(GetRoutingID()));
  RecordAction(UserMetricsAction("SelectAll"));
}
bool RenderWidgetHostImpl::GotResponseToLockMouseRequest(bool allowed) {
  if (!allowed) {
    RejectMouseLockOrUnlockIfNecessary();
    return false;
  } else {
    if (!pending_mouse_lock_request_) {
      // This is possible, e.g., the plugin sends us an unlock request before
      // the user allows to lock to mouse.
      return false;
    }

    pending_mouse_lock_request_ = false;
    if (!view_ || !view_->HasFocus()|| !view_->LockMouse()) {
      Send(new ViewMsg_LockMouse_ACK(routing_id_, false));
      return false;
    } else {
      Send(new ViewMsg_LockMouse_ACK(routing_id_, true));
      return true;
    }
  }
}

// static
void RenderWidgetHostImpl::AcknowledgeSwapBuffers(int32 route_id,
                                                  int gpu_host_id) {
  GpuProcessHostUIShim* ui_shim = GpuProcessHostUIShim::FromID(gpu_host_id);
  if (ui_shim)
    ui_shim->Send(new AcceleratedSurfaceMsg_BuffersSwappedACK(route_id));
}

// static
void RenderWidgetHostImpl::AcknowledgePostSubBuffer(int32 route_id,
                                                    int gpu_host_id) {
  GpuProcessHostUIShim* ui_shim = GpuProcessHostUIShim::FromID(gpu_host_id);
  if (ui_shim)
    ui_shim->Send(new AcceleratedSurfaceMsg_PostSubBufferACK(route_id));
}

void RenderWidgetHostImpl::DelayedAutoResized() {
  gfx::Size new_size = new_auto_size_;
  // Clear the new_auto_size_ since the empty value is used as a flag to
  // indicate that no callback is in progress (i.e. without this line
  // DelayedAutoResized will not get called again).
  new_auto_size_.SetSize(0, 0);
  if (!should_auto_resize_)
    return;

  OnRenderAutoResized(new_size);
}

}  // namespace content