cc: Throttle swaps in Scheduler instead of OutputSurface

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 255128b04b45df40ed030df1886a1f434b2126ac..15ca9d4820a2542c4425abd2076987b1a8e257be 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -61,6 +61,7 @@ class LayerTreeHostImplClient {
  public:
   virtual void UpdateRendererCapabilitiesOnImplThread() = 0;
   virtual void DidLoseOutputSurfaceOnImplThread() = 0;
+  virtual void SetMaxSwapsPending(int max) = 0;
   virtual void DidSwapBuffersOnImplThread() = 0;
   virtual void OnSwapBuffersCompleteOnImplThread() = 0;
   virtual void BeginImplFrame(const BeginFrameArgs& args) = 0;
@@ -224,6 +225,8 @@ class CC_EXPORT LayerTreeHostImpl
   virtual bool DeferredInitialize(
       scoped_refptr<ContextProvider> offscreen_context_provider) OVERRIDE;
   virtual void ReleaseGL() OVERRIDE;
+  virtual void CommitVSyncParameters(base::TimeTicks timebase,
+                                     base::TimeDelta interval) OVERRIDE;
   virtual void SetNeedsRedrawRect(const gfx::Rect& rect) OVERRIDE;
   virtual void BeginImplFrame(const BeginFrameArgs& args) OVERRIDE;
   virtual void SetExternalDrawConstraints(
@@ -536,6 +539,7 @@ class CC_EXPORT LayerTreeHostImpl
 
   scoped_ptr<OutputSurface> output_surface_;
   scoped_refptr<ContextProvider> offscreen_context_provider_;
+  scoped_ptr<BeginFrameSource> begin_frame_source_;
 
   // |resource_provider_| and |tile_manager_| can be NULL, e.g. when using tile-
   // free rendering - see OutputSurface::ForcedDrawToSoftwareDevice().