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

ui/views/controls/scrollbar/base_scroll_bar.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_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_H_
 #define UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_H_
 #pragma once
 
 #include "ui/views/context_menu_controller.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/controls/menu/menu_delegate.h"
@@ skipping 65 matching lines @@
                                       const gfx::Point& p,
                                       bool is_mouse_gesture) OVERRIDE;
 
   // Menu::Delegate overrides:
   virtual string16 GetLabel(int id) const OVERRIDE;
   virtual bool IsCommandEnabled(int id) const OVERRIDE;
   virtual void ExecuteCommand(int id) OVERRIDE;
 
  protected:
   // View overrides:
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE = 0;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE = 0;
 
   BaseScrollBarThumb* GetThumb() const;
 
   CustomButton::ButtonState GetThumbTrackState() const;
 
   // Wrapper functions that calls the controller. We need this since native
   // scrollbars wrap around a different scrollbar. When calling the controller
   // we need to pass in the appropriate scrollbar. For normal scrollbars it's
   // the |this| scrollbar, for native scrollbars it's the native scrollbar used
   // to create this.
@@ skipping 52 matching lines @@
   int context_menu_mouse_position_;
 
   scoped_ptr<MenuRunner> menu_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseScrollBar);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_H_