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

ui/compositor/layer_animation_observer.h

Index: ui/compositor/layer_animation_observer.h
diff --git a/ui/compositor/layer_animation_observer.h b/ui/compositor/layer_animation_observer.h
index 8810090c98c326c91e27c2f17d09f44cdb509033..3484a2c46d870e928e39752b0727f73f93149515 100644
--- a/ui/compositor/layer_animation_observer.h
+++ b/ui/compositor/layer_animation_observer.h
@@ -113,6 +113,10 @@ class COMPOSITOR_EXPORT ImplicitAnimationObserver
   void CheckCompleted();
 
   bool active_;
+
+  // Set to true in the destructor (if non-NULL). Used to detect deletion while
+  // calling out.
+  bool* destroyed_;
 };
 
 }  // namespace ui