cc: Remove retro frames from scheduler.

cc/test/fake_external_begin_frame_source.h

Index: cc/test/fake_external_begin_frame_source.h
diff --git a/cc/test/fake_external_begin_frame_source.h b/cc/test/fake_external_begin_frame_source.h
index 1653decf8cc86465af54b7859f06d9a28e74bff7..f06fb34d47e741a5597a3988267f2427d46ed5e3 100644
--- a/cc/test/fake_external_begin_frame_source.h
+++ b/cc/test/fake_external_begin_frame_source.h
@@ -18,6 +18,7 @@ class FakeExternalBeginFrameSource
   ~FakeExternalBeginFrameSource() override;
 
   // BeginFrameSourceBase overrides.
+  void DidFinishFrame(BeginFrameObserver* obs) override;
   void OnNeedsBeginFramesChanged(bool needs_begin_frames) override;
 
   void TestOnBeginFrame();
@@ -25,6 +26,7 @@ class FakeExternalBeginFrameSource
 
  private:
   double milliseconds_per_frame_;
+  BeginFrameArgs missed_begin_frame_args_;
   base::CancelableClosure begin_frame_task_;
   base::WeakPtrFactory<FakeExternalBeginFrameSource> weak_ptr_factory_;
 };