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

ui/compositor/layer_type.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_TYPE_H_
 #define UI_COMPOSITOR_LAYER_TYPE_H_
 
 namespace ui {
 
 enum LayerType {
   // A layer that has no onscreen representation (note that its children will
   // still be drawn, though).
   LAYER_NOT_DRAWN = 0,
 
   // A layer that has a texture.
   LAYER_TEXTURED = 1,
 
   // A layer that's drawn as a single color.
   LAYER_SOLID_COLOR = 2,
+
+  // A layer based on the NinePatchLayer class.
+  LAYER_NINE_PATCH = 3,
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_TYPE_H_