Make stream captures work on canvases that are not in the DOM.

third_party/WebKit/Source/platform/graphics/ImageBuffer.h

 /*
  * Copyright (C) 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 97 matching lines @@
   void setIsHidden(bool hidden) { m_surface->setIsHidden(hidden); }
 
   // Called by subclasses of ImageBufferSurface to install a new canvas object.
   // Virtual for mocking
   virtual void resetCanvas(PaintCanvas*) const;
 
   PaintCanvas* canvas() const;
   void disableDeferral(DisableDeferralReason) const;
 
   // Called at the end of a task that rendered a whole frame
-  void finalizeFrame(const FloatRect& dirtyRect);
-  void didFinalizeFrame();
-
-  bool isDirty();
+  void finalizeFrame();
+  void doPaintInvalidation(const FloatRect& dirtyRect);
 
   bool writePixels(const SkImageInfo&,
                    const void* pixels,
                    size_t rowBytes,
                    int x,
                    int y);
 
   void willOverwriteCanvas() { m_surface->willOverwriteCanvas(); }
 
   bool getImageData(Multiply, const IntRect&, WTF::ArrayBufferContents&) const;
@@ skipping 85 matching lines @@
   int height() const { return m_size.height(); }
   int width() const { return m_size.width(); }
 
   const unsigned char* m_data;
   const IntSize m_size;
 };
 
 }  // namespace blink
 
 #endif  // ImageBuffer_h