Add Set Authoritative VSync Interval function

cc/scheduler/scheduler.h

Index: cc/scheduler/scheduler.h
diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index dea7c3e541004fd0bce31f182b501ca0e16be845..d4ae2a0ffe9fe50af497372174b3ac3300225a8a 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -167,6 +167,7 @@ class CC_EXPORT Scheduler : public BeginFrameObserverMixIn,
   }
 
   void SetChildrenNeedBeginFrames(bool children_need_begin_frames);
+  void SetAuthoritativeVSyncInterval(base::TimeDelta interval);
 
  protected:
   Scheduler(SchedulerClient* client,
@@ -190,6 +191,7 @@ class CC_EXPORT Scheduler : public BeginFrameObserverMixIn,
   scoped_ptr<SyntheticBeginFrameSource> background_frame_source_internal_;
 
   VSyncParameterObserver* vsync_observer_;
+  base::TimeDelta authoritative_vsync_interval_;
 
   const SchedulerSettings settings_;
   SchedulerClient* client_;