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

ui/views/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 UI_VIEWS_BACKGROUND_H_
 #define UI_VIEWS_BACKGROUND_H_
 #pragma once
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif  // defined(OS_WIN)
 
 #include "base/basictypes.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
-class Canvas;
+class CanvasSkia;
 }
 
 namespace views {
 
 class Painter;
 class View;
 
 /////////////////////////////////////////////////////////////////////////////
 //
 // Background class
@@ skipping 31 matching lines @@
 
   // Creates Chrome's standard panel background
   static Background* CreateStandardPanelBackground();
 
   // Creates a Background from the specified Painter. If owns_painter is
   // true, the Painter is deleted when the Border is deleted.
   static Background* CreateBackgroundPainter(bool owns_painter,
                                              Painter* painter);
 
   // Render the background for the provided view
-  virtual void Paint(gfx::Canvas* canvas, View* view) const = 0;
+  virtual void Paint(gfx::CanvasSkia* canvas, View* view) const = 0;
 
   // Set a solid, opaque color to be used when drawing backgrounds of native
   // controls.  Unfortunately alpha=0 is not an option.
   void SetNativeControlColor(SkColor color);
 
   // Returns the "background color".  This is equivalent to the color set in
   // SetNativeControlColor().  For solid backgrounds, this is the color; for
   // gradient backgrounds, it's the midpoint of the gradient; for painter
   // backgrounds, this is not useful (returns a default color).
   SkColor get_color() const { return color_; }
@@ skipping 11 matching lines @@
   // TODO(port): Create portable replacement for HBRUSH.
   mutable HBRUSH native_control_brush_;
 #endif  // defined(OS_WIN)
 
   DISALLOW_COPY_AND_ASSIGN(Background);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_BACKGROUND_H_