cc/blimp: Add synchronization for scroll/scale state.

blimp/engine/renderer/frame_scheduler.h

Index: blimp/engine/renderer/frame_scheduler.h
diff --git a/blimp/engine/renderer/frame_scheduler.h b/blimp/engine/renderer/frame_scheduler.h
index bfe1a863c403f5fc5bfcf2b6ac4cd6ddd794f74c..5a15b3a31293c2817244e81cb020e9682ff017a0 100644
--- a/blimp/engine/renderer/frame_scheduler.h
+++ b/blimp/engine/renderer/frame_scheduler.h
@@ -52,6 +52,8 @@ class FrameScheduler {
   // Called when an Ack is received for a frame sent to the client.
   void DidReceiveFrameUpdateAck();
 
+  bool needs_frame_update() const { return needs_frame_update_; }
+
  protected:
   // protected for testing.
   FrameScheduler(base::TimeDelta frame_delay,