cc: Remove retro frames from scheduler.

cc/surfaces/display_scheduler.h

Index: cc/surfaces/display_scheduler.h
diff --git a/cc/surfaces/display_scheduler.h b/cc/surfaces/display_scheduler.h
index cd4b5db38789a077c93908202d736e78c51bc5c9..2713ac9c101aa8beac2a71124bb8f614ad15d992 100644
--- a/cc/surfaces/display_scheduler.h
+++ b/cc/surfaces/display_scheduler.h
@@ -27,7 +27,7 @@ class CC_SURFACES_EXPORT DisplaySchedulerClient {
   virtual bool DrawAndSwap() = 0;
 };
 
-class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
+class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserver {
  public:
   DisplayScheduler(DisplaySchedulerClient* client,
                    BeginFrameSource* begin_frame_source,
@@ -46,10 +46,14 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
 
   void OutputSurfaceLost();
 
-  // BeginFrameObserverBase implementation
-  bool OnBeginFrameDerivedImpl(const BeginFrameArgs& args) override;
+  // BeginFrameObserver implementation
+  const BeginFrameArgs& LastUsedBeginFrameArgs() const override;
+  void OnBeginFrame(const BeginFrameArgs& args) override;
   void OnBeginFrameSourcePausedChanged(bool paused) override;
 
+  // TODO(brianderson): Add tracing support.
+  void AsValueInto(base::trace_event::TracedValue* dict) const override {}
+
   BeginFrameSource* begin_frame_source_for_children() {
     return begin_frame_source_for_children_.get();
   }