Add MediaControlsImplTestWithMockScheduler.

third_party/WebKit/Source/modules/media_controls/MediaControlsImplTest.cpp

Index: third_party/WebKit/Source/modules/media_controls/MediaControlsImplTest.cpp
diff --git a/third_party/WebKit/Source/modules/media_controls/MediaControlsImplTest.cpp b/third_party/WebKit/Source/modules/media_controls/MediaControlsImplTest.cpp
index 2c0729d20329dd4e57d0089e1c257bf9e5e66fee..ff07c7bf8fc69c19590cefeda26a00265efa8ab2 100644
--- a/third_party/WebKit/Source/modules/media_controls/MediaControlsImplTest.cpp
+++ b/third_party/WebKit/Source/modules/media_controls/MediaControlsImplTest.cpp
@@ -151,6 +151,8 @@ class MediaControlsImplTest : public ::testing::Test {
     page_holder_->GetFrame().GetSettings()->SetScriptEnabled(true);
   }
 
+  void ResetPage() { page_holder_.reset(); }
+
   void SimulateRouteAvailable() {
     media_controls_->MediaElement().RemoteRouteAvailabilityChanged(
         WebRemotePlaybackAvailability::kDeviceAvailable);
@@ -792,6 +794,8 @@ TEST_F(MediaControlsImplTest, MAYBE_TimelineMetricsDragBackAndForth) {
 }
 
 TEST_F(MediaControlsImplTest, ControlsRemainVisibleDuringKeyboardInteraction) {
+  ResetPage();

[whywhat, 2017/05/29 18:19:53]

This is the line that would likely look confusing to anyone reading this code in
a month from now. Hence I asked for a comment here in my previous reply.

Could we avoid the issue by making ScopedTestingPlatformSupport<> a member of
MediaControlsImplTest reset in SetUp() before InitializePage with a new value?

Then it could be exposed as Platform() to the test case below which won't have
to create a scoped platform or InitializePage() hence avoiding the issue with
PerformanceMonitor.

Something like:

...

class MediaControlsImplTest {
  void SetUp() override {
    testing_platform_ =
MakeUnique<ScopedTestingPlatformSupport<TestingPlatformSupportWithMockScheduler>>();
    InitializePage();
  }

  ScopedTestingPlatformSupport* Platform() { return testing_platform_.get(); }

  ...

 private:
 
unique_ptr<ScopedTestingPlatformSupport<TestingPlatformSupportWithMockScheduler>>
testing_platform_;
  ...
};

...

TEST_F(MediaControlsImplTest, ControlsRemainVisibleDuringKeyboardInteraction) {
  // DocumentParserTiming has DCHECKS to make sure time > 0.0.
  Platform()->AdvanceClockSeconds(1);
  EnsureSizing();

  Element* panel = MediaControls().PanelElement();

  ...
  Platform()->RunForPeriodSeconds(2);
  ...
}

+
   ScopedTestingPlatformSupport<TestingPlatformSupportWithMockScheduler>
       platform;