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

ui/views/border.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_VIEWS_BORDER_H_
 #define UI_VIEWS_BORDER_H_
 #pragma once
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/insets.h"
 #include "ui/views/view.h"
 
 namespace gfx{
-class Canvas;
+class CanvasSkia;
 }
 
 namespace views {
 
 class Painter;
 class View;
 
 ////////////////////////////////////////////////////////////////////////////////
 //
 // Border class.
@@ skipping 27 matching lines @@
   // side.
   static Border* CreateSolidSidedBorder(int top, int left,
       int bottom, int right,
       SkColor color);
 
   // Creates a Border from the specified Painter. The border owns the painter,
   // thus the painter is deleted when the Border is deleted.
   static Border* CreateBorderPainter(Painter* painter);
 
   // Renders the border for the specified view.
-  virtual void Paint(const View& view, gfx::Canvas* canvas) const = 0;
+  virtual void Paint(const View& view, gfx::CanvasSkia* canvas) const = 0;
 
   // Sets the specified insets to the the border insets.
   virtual void GetInsets(gfx::Insets* insets) const = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Border);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_BORDER_H_