// Copyright 2018 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 "base/base_switches.h"
#include "base/command_line.h"
#include "base/macros.h"
#include "base/run_loop.h"
#include "build/build_config.h"
#include "chrome/browser/ui/browser.h"
#include "chrome/browser/ui/tabs/tab_strip_model.h"
#include "chrome/test/base/in_process_browser_test.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_observer.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace {

class RunLoopUntilNonEmptyPaint : public content::WebContentsObserver {
 public:
  explicit RunLoopUntilNonEmptyPaint(content::WebContents* web_contents)
      : content::WebContentsObserver(web_contents) {}

  ~RunLoopUntilNonEmptyPaint() override = default;

  // Runs a RunLoop on the main thread until the first non-empty frame is
  // painted for the WebContents provided to the constructor.
  void RunUntilIdle() { run_loop_.Run(); }

 private:
  // content::WebContentsObserver:
  void DidFirstVisuallyNonEmptyPaint() override { run_loop_.Quit(); }

  base::RunLoop run_loop_;

  DISALLOW_COPY_AND_ASSIGN(RunLoopUntilNonEmptyPaint);
};

class NoBackgroundTasksTest : public InProcessBrowserTest {
 protected:
  NoBackgroundTasksTest() = default;
  ~NoBackgroundTasksTest() override = default;

 private:
  void SetUpCommandLine(base::CommandLine* command_line) override {
    command_line->AppendSwitch(switches::kDisableBackgroundTasks);
  }

  DISALLOW_COPY_AND_ASSIGN(NoBackgroundTasksTest);
};

}  // namespace

// Verify that it is possible to get the first non-empty paint without running
// background tasks.
//
// TODO(fdoray): Enable on ChromeOS once all dependencies on background tasks to
// produce the first non-empty paint have been removed. https://crbug.com/831835
// This test is flaky on Mac: https://crbug.com/833989
#if defined(OS_CHROMEOS) || defined(OS_MACOSX)
#define MAYBE_FirstNonEmptyPaintWithoutBackgroundTasks \
  DISABLED_FirstNonEmptyPaintWithoutBackgroundTasks
#else
#define MAYBE_FirstNonEmptyPaintWithoutBackgroundTasks \
  FirstNonEmptyPaintWithoutBackgroundTasks
#endif
IN_PROC_BROWSER_TEST_F(NoBackgroundTasksTest,
                       MAYBE_FirstNonEmptyPaintWithoutBackgroundTasks) {
  RunLoopUntilNonEmptyPaint run_loop_until_non_empty_paint(
      browser()->tab_strip_model()->GetActiveWebContents());
  run_loop_until_non_empty_paint.RunUntilIdle();
}