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

chrome/browser/ui/views/theme_background.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 CHROME_BROWSER_UI_VIEWS_THEME_BACKGROUND_H_
 #define CHROME_BROWSER_UI_VIEWS_THEME_BACKGROUND_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "ui/views/background.h"
 
@@ skipping 12 matching lines @@
 // image. It takes care of active/inactive state, incognito state and
 // the offset from the frame view.
 //
 ////////////////////////////////////////////////////////////////////////////////
 class ThemeBackground : public views::Background {
  public:
   explicit ThemeBackground(BrowserView* browser);
   virtual ~ThemeBackground() {}
 
   // Overridden from views:;Background.
-  virtual void Paint(gfx::Canvas* canvas, views::View* view) const OVERRIDE;
+  virtual void Paint(gfx::CanvasSkia* canvas, views::View* view) const OVERRIDE;
 
  private:
   BrowserView* browser_view_;
 
   DISALLOW_COPY_AND_ASSIGN(ThemeBackground);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_THEME_BACKGROUND_H_