cc: Handle retroactive BeginFrames in the Scheduler.

cc/trees/single_thread_proxy.h

Index: cc/trees/single_thread_proxy.h
diff --git a/cc/trees/single_thread_proxy.h b/cc/trees/single_thread_proxy.h
index 462bdd2d0d007626ba57d26afb4d42f4b407db0e..7bedc494c5620158c0dfe8cbaf0a39adde2e5896 100644
--- a/cc/trees/single_thread_proxy.h
+++ b/cc/trees/single_thread_proxy.h
@@ -58,8 +58,7 @@ class SingleThreadProxy : public Proxy, LayerTreeHostImplClient {
   virtual void DidLoseOutputSurfaceOnImplThread() OVERRIDE;
   virtual void DidSwapBuffersOnImplThread() OVERRIDE;
   virtual void OnSwapBuffersCompleteOnImplThread() OVERRIDE;
-  virtual void BeginImplFrame(const BeginFrameArgs& args)
-      OVERRIDE {}
+  virtual void BeginFrame(const BeginFrameArgs& args) OVERRIDE {}
   virtual void OnCanDrawStateChanged(bool can_draw) OVERRIDE;
   virtual void NotifyReadyToActivate() OVERRIDE;
   virtual void SetNeedsRedrawOnImplThread() OVERRIDE;