Change ui::wm::Shadow to use cc::NinePatchLayer.

ui/wm/core/shadow.h

Index: ui/wm/core/shadow.h
diff --git a/ui/wm/core/shadow.h b/ui/wm/core/shadow.h
index c153ecf158e42d58e641c8630d58ce6bdbd47e42..859ac05bf7622b81d69298f87b8ac0dfeb9ba61c 100644
--- a/ui/wm/core/shadow.h
+++ b/ui/wm/core/shadow.h
@@ -17,8 +17,6 @@ class Layer;
 
 namespace wm {
 
-class ImageGrid;
-
 // Simple class that draws a drop shadow around content at given bounds.
 class WM_EXPORT Shadow : public ui::ImplicitAnimationObserver {
  public:
@@ -40,16 +38,16 @@ class WM_EXPORT Shadow : public ui::ImplicitAnimationObserver {
 
   void Init(Style style);
 
-  // Returns |image_grid_|'s ui::Layer.  This is exposed so it can be added to
-  // the same layer as the content and stacked below it.  SetContentBounds()
-  // should be used to adjust the shadow's size and position (rather than
-  // applying transformations to this layer).
-  ui::Layer* layer() const;
+  // Returns |layer_.get()|. This is exposed so it can be added to the same
+  // layer as the content and stacked below it.  SetContentBounds() should be
+  // used to adjust the shadow's size and position (rather than applying
+  // transformations to this layer).
+  ui::Layer* layer() const { return layer_.get(); }
 
   const gfx::Rect& content_bounds() const { return content_bounds_; }
   Style style() const { return style_; }
 
-  // Moves and resizes |image_grid_| to frame |content_bounds|.
+  // Moves and resizes the shadow layer to frame |content_bounds|.
   void SetContentBounds(const gfx::Rect& content_bounds);
 
   // Sets the shadow's style, animating opacity as necessary.
@@ -59,17 +57,17 @@ class WM_EXPORT Shadow : public ui::ImplicitAnimationObserver {
   virtual void OnImplicitAnimationsCompleted() OVERRIDE;
 
  private:
-  // Updates the |image_grid_| images to the current |style_|.
+  // Updates the shadow images to the current |style_|.
   void UpdateImagesForStyle();
 
-  // Updates the |image_grid_| bounds based on its image sizes and the
-  // current |content_bounds_|.
-  void UpdateImageGridBounds();
+  // Updates the image bounds based on its image sizes and the current
+  // |content_bounds_|.
+  void UpdateImageBounds();
 
   // The current style, set when the transition animation starts.
   Style style_;
 
-  scoped_ptr<ImageGrid> image_grid_;
+  scoped_ptr<ui::Layer> layer_;
 
   // Bounds of the content that the shadow encloses.
   gfx::Rect content_bounds_;