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

ui/views/drag_utils.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_DRAG_UTILS_H_
 #define UI_VIEWS_DRAG_UTILS_H_
 #pragma once
 
 #include <string>
 
 #include "base/file_path.h"
 #include "base/string16.h"
 #include "ui/views/views_export.h"
 
 class GURL;
 class SkBitmap;
 
 namespace gfx {
-class Canvas;
+class CanvasSkia;
 class Point;
 class Size;
 }
 
 namespace ui {
 class OSExchangeData;
 }
 using ui::OSExchangeData;
 
 namespace drag_utils {
 
 // Sets url and title on data as well as setting a suitable image for dragging.
 // The image looks like that of the bookmark buttons.
 VIEWS_EXPORT void SetURLAndDragImage(const GURL& url,
                                      const string16& title,
                                      const SkBitmap& icon,
                                      ui::OSExchangeData* data);
 
 // Creates a dragging image to be displayed when the user drags a file from
 // Chrome (via the download manager, for example). The drag image is set into
 // the supplied data_object. 'file_name' can be a full path, but the directory
 // portion will be truncated in the drag image.
 VIEWS_EXPORT void CreateDragImageForFile(const FilePath& file_name,
                                          const SkBitmap* icon,
                                          ui::OSExchangeData* data_object);
 
 // Sets the drag image on data_object from the supplied canvas. width/height
 // are the size of the image to use, and the offsets give the location of
 // the hotspot for the drag image.
-VIEWS_EXPORT void SetDragImageOnDataObject(const gfx::Canvas& canvas,
+VIEWS_EXPORT void SetDragImageOnDataObject(const gfx::CanvasSkia& canvas,
                                            const gfx::Size& size,
                                            const gfx::Point& cursor_offset,
                                            ui::OSExchangeData* data_object);
 
 // Sets the drag image on data_object from the supplied bitmap. width/height
 // are the size of the image to use, and the offsets give the location of
 // the hotspot for the drag image.
 VIEWS_EXPORT void SetDragImageOnDataObject(const SkBitmap& bitmap,
                                            const gfx::Size& size,
                                            const gfx::Point& cursor_offset,
                                            ui::OSExchangeData* data_object);
 
 }  // namespace drag_utils
 
 #endif  // UI_VIEWS_DRAG_UTILS_H_