ash: Improved window maximize/restore animations

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 e46010177f725f55f5a6fcbe68227abae231476a..dc5393ef55be7e21e01923810b959c4a603f52a7 100644
--- a/ui/compositor/compositor_observer.h
+++ b/ui/compositor/compositor_observer.h
@@ -22,6 +22,9 @@ class COMPOSITOR_EXPORT CompositorObserver {
   // Called when compositing completes: the present to screen has completed.
   virtual void OnCompositingEnded(Compositor* compositor) = 0;
 
+  // Called when compositing is aborted (e.g. lost graphics context).
+  virtual void OnCompositingAborted(Compositor* compositor) = 0;
+
  protected:
   virtual ~CompositorObserver() {}
 };