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

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

 // Copyright 2014 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 RecordingImageBufferSurface_h
 #define RecordingImageBufferSurface_h
 
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/ImageBufferSurface.h"
 #include "public/platform/WebThread.h"
@@ skipping 47 matching lines @@
   void flush(FlushReason) override;
   void didDraw(const FloatRect&) override;
   bool isValid() const override { return true; }
   bool isRecording() const override { return !m_fallbackSurface; }
   bool writePixels(const SkImageInfo& origInfo,
                    const void* pixels,
                    size_t rowBytes,
                    int x,
                    int y) override;
   void willOverwriteCanvas() override;
-  virtual void finalizeFrame(const FloatRect&);
+  void finalizeFrame() override;
+  void doPaintInvalidation(const FloatRect&) override;
   void setImageBuffer(ImageBuffer*) override;
   sk_sp<SkImage> newImageSnapshot(AccelerationHint, SnapshotReason) override;
   void draw(GraphicsContext&,
             const FloatRect& destRect,
             const FloatRect& srcRect,
             SkBlendMode) override;
   bool isExpensiveToPaint() override;
   void setHasExpensiveOp() override { m_currentFrameHasExpensiveOp = true; }
 
   // Passthroughs to fallback surface
@@ skipping 55 matching lines @@
   bool m_frameWasCleared;
   bool m_didRecordDrawCommandsInCurrentFrame;
   bool m_currentFrameHasExpensiveOp;
   bool m_previousFrameHasExpensiveOp;
   std::unique_ptr<RecordingImageBufferFallbackSurfaceFactory> m_fallbackFactory;
 };
 
 }  // namespace blink
 
 #endif