aura: fast resizes for accelerated pages

ui/gfx/compositor/compositor.h

Index: ui/gfx/compositor/compositor.h
diff --git a/ui/gfx/compositor/compositor.h b/ui/gfx/compositor/compositor.h
index f4b711c3ae0fd7e482741bbfc4b406e20979fc3f..1a2422ac3c6f079fcf2f6f7e7627e3155f8cd80a 100644
--- a/ui/gfx/compositor/compositor.h
+++ b/ui/gfx/compositor/compositor.h
@@ -170,6 +170,10 @@ class COMPOSITOR_EXPORT Compositor
   void RemoveObserver(CompositorObserver* observer);
   bool HasObserver(CompositorObserver* observer);
 
+  // Returns whether a draw is pending, that is, if we're between the Draw call
+  // and the OnCompositingEnded.
+  bool DrawPending() const { return swap_posted_; }
+
   // Internal functions, called back by command-buffer contexts on swap buffer
   // events.