Allow DrawingBuffer to present to a bitmap.

Source/core/platform/graphics/gpu/DrawingBuffer.h

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 107 matching lines @@
     Platform3DObject framebuffer() const;
 
     void markContentsChanged() { m_contentsChanged = true; }
 
     WebKit::WebLayer* platformLayer();
     void paintCompositedResultsToCanvas(ImageBuffer*);
 
     // WebExternalTextureLayerClient implementation.
     virtual unsigned prepareTexture(WebKit::WebTextureUpdater& updater) OVERRIDE;
     virtual WebKit::WebGraphicsContext3D* context() OVERRIDE;
-    virtual bool prepareMailbox(WebKit::WebExternalTextureMailbox*) OVERRIDE;
+    virtual bool prepareMailbox(WebKit::WebExternalTextureMailbox*, bool bitmap) OVERRIDE;
     virtual void mailboxReleased(const WebKit::WebExternalTextureMailbox&) OVERRIDE;
 
 private:
     DrawingBuffer(GraphicsContext3D*, const IntSize&, bool multisampleExtensionSupported,
                   bool packedDepthStencilExtensionSupported, PreserveDrawingBuffer, PassRefPtr<ContextEvictionManager>);
 
     void initialize(const IntSize&);
 
     void prepareBackBuffer();
     bool requiresCopyFromBackToFrontBuffer() const;
@@ skipping 68 matching lines @@
     // Mailboxes that were released by the compositor and can be used again by this DrawingBuffer.
     Vector<RefPtr<MailboxInfo> > m_recycledMailboxes;
     RefPtr<MailboxInfo> m_lastColorBuffer;
 
     RefPtr<ContextEvictionManager> m_contextEvictionManager;
 };
 
 } // namespace WebCore
 
 #endif // DrawingBuffer_h