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

ash/wm/partial_screenshot_view.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 ASH_WM_PARTIAL_SCREENSHOT_VIEW_H_
 #define ASH_WM_PARTIAL_SCREENSHOT_VIEW_H_
 #pragma once
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
@@ skipping 19 matching lines @@
 
   // Overriddden from View:
   virtual gfx::NativeCursor GetCursor(const views::MouseEvent& event) OVERRIDE;
 
  private:
   gfx::Rect GetScreenshotRect() const;
 
   void set_window(aura::Window* window) { window_ = window; }
 
   // Overridden from View:
-  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;
   virtual bool OnMouseWheel(const views::MouseWheelEvent& event) OVERRIDE;
   virtual void OnMouseReleased(const views::MouseEvent& event) OVERRIDE;
 
   bool is_dragging_;
   gfx::Point start_position_;
   gfx::Point current_position_;
   ScreenshotDelegate* screenshot_delegate_;
   aura::Window* window_;
 
   DISALLOW_COPY_AND_ASSIGN(PartialScreenshotView);
 };
 
 }  // namespace ash
 
 #endif  // #ifndef ASH_WM_PARTIAL_SCREENSHOT_VIEW_H_