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

chrome/browser/ntp_background_util.h

-// Copyright (c) 2009 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_NTP_BACKGROUND_UTIL_H_
 #define CHROME_BROWSER_NTP_BACKGROUND_UTIL_H_
 #pragma once
 
 namespace gfx {
-class Canvas;
+class CanvasSkia;
 class Rect;
 }
 
 namespace ui {
 class ThemeProvider;
 }
 
 class NtpBackgroundUtil {
  public:
   // Paints the NTP background on |canvas|. |area| is the area of the canvas
   // that gets painted and also serves as the origin of the image (for top-
   // aligned images). |tab_contents_height| is necessary for correctly painting
   // bottom-aligned images since then the origin is the bottom of the web page.
-  static void PaintBackgroundDetachedMode(
-      ui::ThemeProvider* tp, gfx::Canvas* canvas,
-      const gfx::Rect& area, int tab_contents_height);
+  static void PaintBackgroundDetachedMode(ui::ThemeProvider* tp,
+                                          gfx::CanvasSkia* canvas,
+                                          const gfx::Rect& area,
+                                          int tab_contents_height);
 
  private:
   NtpBackgroundUtil() {}
 };
 
 #endif  // CHROME_BROWSER_NTP_BACKGROUND_UTIL_H_