Attempt 2 at Fixes crash introduced @ 153047 (you can hit crash by maximizing a

ui/compositor/layer_animation_observer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_COMPOSITOR_LAYER_ANIMATION_OBSERVER_H_
 #define UI_COMPOSITOR_LAYER_ANIMATION_OBSERVER_H_
 
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 95 matching lines @@
   virtual void OnDetachedFromSequence(
       LayerAnimationSequence* sequence) OVERRIDE;
 
   // OnImplicitAnimationsCompleted is not fired unless the observer is active.
   bool active() const { return active_; }
   void SetActive(bool active);
 
   void CheckCompleted();
 
   bool active_;
+
+  // Set to true in the destructor (if non-NULL). Used to detect deletion while
+  // calling out.
+  bool* destroyed_;
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_ANIMATION_OBSERVER_H_