Tighter sync and faster ACK on SwapBuffers/PostSubBuffers

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index 33f6d6b6c3a9ef78348b56518b734b91809b4d01..03552de358fb22112c66eda0834b4b978490ea96 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -214,6 +214,10 @@ class COMPOSITOR_EXPORT Compositor
   virtual void didCompleteSwapBuffers();
   virtual void scheduleComposite();
 
+  int last_started_id() { return last_started_id_; }
+  int last_will_end_id() { return last_will_end_id_; }
+  int last_ended_id() { return last_ended_id_; }
+
  private:
   friend class base::RefCounted<Compositor>;
 
@@ -244,6 +248,10 @@ class COMPOSITOR_EXPORT Compositor
   // The device scale factor of the monitor that this compositor is compositing
   // layers on.
   float device_scale_factor_;
+
+  int last_started_id_;

[piman, 2012/06/04 18:20:39]

naming bikeshedding: mind calling these
last_started_frame_/last_will_end_frame_/last_ended_frame_ ? From outside the
class (e.g. in root_window.cc), it's very non-obvious what these "ids" refer to.

+  int last_will_end_id_;
+  int last_ended_id_;
 };
 
 }  // namespace ui