cc: Remove retro frames from scheduler.

cc/scheduler/scheduler.h

Index: cc/scheduler/scheduler.h
diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index 9aade7e2d454f548864e7d559a8b29a55b801cd9..c4cc5ef2597c47aa6c09b73eb199c55007494eba 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -53,7 +53,7 @@ class SchedulerClient {
   virtual ~SchedulerClient() {}
 };
 
-class CC_EXPORT Scheduler : public BeginFrameObserverBase {
+class CC_EXPORT Scheduler : public BeginFrameObserver {
  public:
   static std::unique_ptr<Scheduler> Create(
       SchedulerClient* client,
@@ -65,9 +65,10 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
 
   ~Scheduler() override;
 
-  // BeginFrameObserverBase
+  // BeginFrameObserver
+  const BeginFrameArgs& LastUsedBeginFrameArgs() const override;
   void OnBeginFrameSourcePausedChanged(bool paused) override;
-  bool OnBeginFrameDerivedImpl(const BeginFrameArgs& args) override;
+  void OnBeginFrame(const BeginFrameArgs& args) override;
 
   void OnDrawForOutputSurface(bool resourceless_software_draw);
 
@@ -169,15 +170,12 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
   std::unique_ptr<CompositorTimingHistory> compositor_timing_history_;
   base::TimeDelta estimated_parent_draw_time_;
 
-  std::deque<BeginFrameArgs> begin_retro_frame_args_;
   SchedulerStateMachine::BeginImplFrameDeadlineMode
       begin_impl_frame_deadline_mode_;
   BeginFrameTracker begin_impl_frame_tracker_;
   BeginFrameArgs begin_main_frame_args_;
 
-  base::Closure begin_retro_frame_closure_;
   base::Closure begin_impl_frame_deadline_closure_;
-  base::CancelableClosure begin_retro_frame_task_;
   base::CancelableClosure begin_impl_frame_deadline_task_;
 
   SchedulerStateMachine state_machine_;
@@ -189,10 +187,10 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
   void ScheduleBeginImplFrameDeadlineIfNeeded();
   void BeginImplFrameNotExpectedSoon();
   void SetupNextBeginFrameIfNeeded();
-  void PostBeginRetroFrameIfNeeded();
   void DrawAndSwapIfPossible();
   void DrawAndSwapForced();
   void ProcessScheduledActions();
+  void PerformAction(SchedulerStateMachine::Action action);
   void UpdateCompositorTimingHistoryRecordingEnabled();
   bool ShouldRecoverMainLatency(const BeginFrameArgs& args,
                                 bool can_activate_before_deadline) const;
@@ -203,7 +201,6 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
       base::TimeDelta bmf_to_activate_estimate) const;
   void AdvanceCommitStateIfPossible();
   bool IsBeginMainFrameSentOrStarted() const;
-  void BeginRetroFrame();
   void BeginImplFrameWithDeadline(const BeginFrameArgs& args);
   void BeginImplFrameSynchronous(const BeginFrameArgs& args);
   void BeginImplFrame(const BeginFrameArgs& args);