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

ui/views/controls/slider.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_CONTROLS_SLIDER_H_
 #define UI_VIEWS_CONTROLS_SLIDER_H_
 #pragma once
 
 #include "ui/views/view.h"
 #include "ui/views/views_export.h"
@@ skipping 29 matching lines @@
   virtual ~Slider();
 
   float value() const { return value_; }
   void SetValue(float value);
 
  private:
   void SetValueInternal(float value, SliderChangeReason reason);
 
   // views::View overrides:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE;
   virtual bool OnMousePressed(const views::MouseEvent& event) OVERRIDE;
   virtual bool OnMouseDragged(const views::MouseEvent& event) OVERRIDE;
 
   SliderListener* listener_;
   Orientation orientation_;
 
   float value_;
 
   DISALLOW_COPY_AND_ASSIGN(Slider);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SLIDER_H_