cc: Cleanup DelayBasedTimeSource code.

cc/scheduler/begin_frame_source.h

Index: cc/scheduler/begin_frame_source.h
diff --git a/cc/scheduler/begin_frame_source.h b/cc/scheduler/begin_frame_source.h
index 9eb3ea279daf7c6d04b656d06c25b87d65a94b50..ff3452a4f1f542d96da348b9e7abf741ba59aa35 100644
--- a/cc/scheduler/begin_frame_source.h
+++ b/cc/scheduler/begin_frame_source.h
@@ -207,7 +207,7 @@ class CC_EXPORT BackToBackBeginFrameSource : public BeginFrameSourceBase {
 // A frame source which is locked to an external parameters provides from a
 // vsync source and generates BeginFrameArgs for it.
 class CC_EXPORT SyntheticBeginFrameSource : public BeginFrameSourceBase,
-                                            public TimeSourceClient {
+                                            public DelayBasedTimeSourceClient {
  public:
   static scoped_ptr<SyntheticBeginFrameSource> Create(
       base::SingleThreadTaskRunner* task_runner,
@@ -220,11 +220,13 @@ class CC_EXPORT SyntheticBeginFrameSource : public BeginFrameSourceBase,
   // Tracing
   void AsValueInto(base::trace_event::TracedValue* dict) const override;
 
-  // TimeSourceClient
+  // DelayBasedTimeSourceClient
+  void OnMissedTick() override;
   void OnTimerTick() override;
 
  protected:
   explicit SyntheticBeginFrameSource(
+      base::SingleThreadTaskRunner* task_runner,
       scoped_ptr<DelayBasedTimeSource> time_source);
 
   BeginFrameArgs CreateBeginFrameArgs(base::TimeTicks frame_time,
@@ -233,9 +235,12 @@ class CC_EXPORT SyntheticBeginFrameSource : public BeginFrameSourceBase,
   // BeginFrameSourceBase
   void OnNeedsBeginFramesChange(bool needs_begin_frames) override;
 
+  base::SingleThreadTaskRunner* task_runner_;
   scoped_ptr<DelayBasedTimeSource> time_source_;
 
  private:
+  base::WeakPtrFactory<SyntheticBeginFrameSource> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(SyntheticBeginFrameSource);
 };