LayerAnimator must be prepared for its owning layer's deletion whenever it notifies observers.

ui/compositor/layer.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_H_
 #define UI_COMPOSITOR_LAYER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 357 matching lines @@
   Layer* layer_mask_;
   // The back link from the mask layer to it's associated masked layer.
   // We keep this reference for the case that if the mask layer gets deleted
   // while attached to the main layer before the main layer is deleted.
   Layer* layer_mask_back_link_;
 
   std::string name_;
 
   LayerDelegate* delegate_;
 
-  scoped_ptr<LayerAnimator> animator_;
+  scoped_refptr<LayerAnimator> animator_;
 
   // Ownership of the layer is held through one of the strongly typed layer
   // pointers, depending on which sort of layer this is.
   scoped_ptr<WebKit::WebContentLayer> content_layer_;
   scoped_ptr<WebKit::WebExternalTextureLayer> texture_layer_;
   scoped_ptr<WebKit::WebSolidColorLayer> solid_color_layer_;
   WebKit::WebLayer* web_layer_;
   bool web_layer_is_accelerated_;
   bool show_debug_borders_;
 
   // If true, the layer scales the canvas and the texture with the device scale
   // factor as appropriate. When true, the texture size is in DIP.
   bool scale_content_;
 
   // A cached copy of |Compositor::device_scale_factor()|.
   float device_scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_H_