Introduce PlatformBitmap, which is a minimal helper class that wraps an SkBitmap

content/browser/renderer_host/render_widget_host_view_mac.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 CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 #include <list>
 #include <map>
@@ skipping 241 matching lines @@
   virtual void Destroy() OVERRIDE;
   virtual void SetTooltipText(const string16& tooltip_text) OVERRIDE;
   virtual void SelectionChanged(const string16& text,
                                 size_t offset,
                                 const ui::Range& range) OVERRIDE;
   virtual BackingStore* AllocBackingStore(const gfx::Size& size) OVERRIDE;
   virtual void CopyFromCompositingSurface(
       const gfx::Rect& src_subrect,
       const gfx::Size& dst_size,
       const base::Callback<void(bool)>& callback,
-      skia::PlatformCanvas* output) OVERRIDE;
+      skia::PlatformBitmap* output) OVERRIDE;
   virtual void OnAcceleratedCompositingStateChange() OVERRIDE;
 
   virtual void OnAccessibilityNotifications(
       const std::vector<AccessibilityHostMsg_NotificationParams>& params
       ) OVERRIDE;
 
   virtual void PluginFocusChanged(bool focused, int plugin_id) OVERRIDE;
   virtual void StartPluginIme() OVERRIDE;
   virtual bool PostProcessEventForPluginIme(
       const NativeWebKeyboardEvent& event) OVERRIDE;
@@ skipping 203 matching lines @@
 
   // The current caret bounds.
   gfx::Rect caret_rect_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewMac);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_