Aura: Resize locks with --ui-enable-threaded-compositing

ui/compositor/compositor_observer.h

Index: ui/compositor/compositor_observer.h
diff --git a/ui/compositor/compositor_observer.h b/ui/compositor/compositor_observer.h
index 830f170ca22d8c69336ab08a4003c64fa3146829..4157453ec6004d0224dfce198f04a635e2921c7b 100644
--- a/ui/compositor/compositor_observer.h
+++ b/ui/compositor/compositor_observer.h
@@ -19,12 +19,10 @@ class COMPOSITOR_EXPORT CompositorObserver {
   // composite. In the multi-threaded case, many commits may happen between
   // two successive composites. In the single-threaded, a single commit
   // between two composites (just before the composite as part of the
-  // composite cycle).
+  // composite cycle). If the compositor is locked, it will not send this
+  // this signal.
   virtual void OnCompositingDidCommit(Compositor* compositor) = 0;
 
-  // Called when compositing will start.
-  virtual void OnCompositingWillStart(Compositor* compositor) = 0;
-
   // Called when compositing started: it has taken all the layer changes into
   // account and has issued the graphics commands.
   virtual void OnCompositingStarted(Compositor* compositor) = 0;
@@ -35,6 +33,9 @@ class COMPOSITOR_EXPORT CompositorObserver {
   // Called when compositing is aborted (e.g. lost graphics context).
   virtual void OnCompositingAborted(Compositor* compositor) = 0;
 
+  // Called when the compositor lock state changes.
+  virtual void OnCompositingLockStateChanged(Compositor* compositor) = 0;
+
  protected:
   virtual ~CompositorObserver() {}
 };