Hoist begin frame sources out of 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 3b69668f69969d7b7101a3fbde0a77f599b4cad0..66e00758a517fb4ab76031b544ee75577f9ff107 100644
--- a/cc/trees/single_thread_proxy.h
+++ b/cc/trees/single_thread_proxy.h
@@ -145,8 +145,13 @@ class CC_EXPORT SingleThreadProxy : public Proxy,
 
   // Accessed from both threads.
   scoped_ptr<BeginFrameSource> external_begin_frame_source_;
+  scoped_ptr<BeginFrameSource> unthrottled_begin_frame_source_;
+  scoped_ptr<SyntheticBeginFrameSource> synthetic_begin_frame_source_;
   scoped_ptr<Scheduler> scheduler_on_impl_thread_;
 
+  base::TimeDelta authoritative_vsync_interval_;
+  base::TimeTicks last_vsync_timebase_;
+
   scoped_ptr<BlockingTaskRunner::CapturePostTasks> commit_blocking_task_runner_;
   bool next_frame_is_newly_committed_frame_;