ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ash/wm/image_grid.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 ASH_WM_IMAGE_GRID_H_
 #define ASH_WM_IMAGE_GRID_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
@@ skipping 118 matching lines @@
   class ImagePainter : public ui::LayerDelegate {
    public:
     ImagePainter(const gfx::Image* image) : image_(image) {}
     virtual ~ImagePainter() {}
 
     // Clips |layer| to |clip_rect|.  Triggers a repaint if the clipping
     // rectangle has changed.  An empty rectangle disables clipping.
     void SetClipRect(const gfx::Rect& clip_rect, ui::Layer* layer);
 
     // ui::LayerDelegate implementation:
-    virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE;
+    virtual void OnPaintLayer(gfx::CanvasSkia* canvas) OVERRIDE;
 
    private:
     friend class TestAPI;
 
     const gfx::Image* image_;  // not owned
 
     gfx::Rect clip_rect_;
 
     DISALLOW_COPY_AND_ASSIGN(ImagePainter);
   };
@@ skipping 56 matching lines @@
   scoped_ptr<ImagePainter> bottom_painter_;
   scoped_ptr<ImagePainter> bottom_right_painter_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageGrid);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_IMAGE_GRID_H_