Retain tray bubble's rounded corners when the bubble animates out

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 180 matching lines @@
   // Invert the layer.
   bool layer_inverted() const { return layer_inverted_; }
   void SetLayerInverted(bool inverted);
 
   // Return the target opacity if animator is running, or the current opacity
   // otherwise.
   float GetTargetOpacity() const;
 
   // Set a layer mask for a layer.
   // Note the provided layer mask can neither have a layer mask itself nor can
-  // it have any children. The ownership of |layer_mask| will not be
-  // transferred with this call.
+  // it have any children.
   // Furthermore: A mask layer can only be set to one layer.
-  void SetMaskLayer(Layer* layer_mask);
-  Layer* layer_mask_layer() { return layer_mask_; }
+  void SetMaskLayer(scoped_ptr<Layer> layer_mask);
+  Layer* layer_mask_layer() { return layer_mask_.get(); }
 
   // Sets the visibility of the Layer. A Layer may be visible but not
   // drawn. This happens if any ancestor of a Layer is not visible.
   void SetVisible(bool visible);
   bool visible() const { return visible_; }
 
   // Returns the target visibility if the animator is running. Otherwise, it
   // returns the current visibility.
   bool GetTargetVisibility() const;
 
@@ skipping 226 matching lines @@
 
   int background_blur_radius_;
 
   // Several variables which will change the visible representation of
   // the layer.
   float layer_saturation_;
   float layer_brightness_;
   float layer_grayscale_;
   bool layer_inverted_;
 
-  // The associated mask layer with this layer.
-  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_;
+  // The mask layer associated with this layer.
+  scoped_ptr<Layer> layer_mask_;
 
   // The zoom factor to scale the layer by.  Zooming is disabled when this is
   // set to 1.
   float zoom_;
 
   // Width of the border in pixels, where the scaling is blended.
   int zoom_inset_;
 
   std::string name_;
 
@@ skipping 29 matching lines @@
   // The size of the delegated frame in DIP, set when SetShowDelegatedContent
   // was called.
   gfx::Size delegated_frame_size_in_dip_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_H_