Move overdraw tracking code from GraphicsContext to CanvasRenderingContext2D

Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * 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 137 matching lines @@
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) override;
 
     // DocumentVisibilityObserver implementation
     virtual void didChangeVisibilityState(PageVisibilityState) override;
 
     // CanvasImageSource implementation
     virtual PassRefPtr<Image> getSourceImageForCanvas(SourceImageMode, SourceImageStatus*) const override;
     virtual bool wouldTaintOrigin(SecurityOrigin*) const override;
     virtual FloatSize sourceSize() const override;
     virtual bool isCanvasElement() const override { return true; }
+    virtual bool isOpaque() const override;
 
     // ImageBufferClient implementation
     virtual void notifySurfaceInvalid() override;
     virtual bool isDirty() override { return !m_dirtyRect.isEmpty(); }
     virtual void didFinalizeFrame() override;
     virtual void restoreCanvasMatrixClipStack() override;
 
     void doDeferredPaintInvalidation();
 
     virtual void trace(Visitor*) override;
 
+    // Methods used for testing
+    void createImageBufferUsingSurface(PassOwnPtr<ImageBufferSurface>);
+
 protected:
     virtual void didMoveToNewDocument(Document& oldDocument) override;
 
 private:
     explicit HTMLCanvasElement(Document&);
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
     virtual LayoutObject* createRenderer(const RenderStyle&) override;
     virtual void didRecalcStyle(StyleRecalcChange) override;
     virtual bool areAuthorShadowsAllowed() const override { return false; }
 
     void reset();
 
     PassOwnPtr<RecordingImageBufferFallbackSurfaceFactory> createSurfaceFactory(const IntSize& deviceSize, int* msaaSampleCount) const;
     PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
     void createImageBuffer();
-    void createImageBufferInternal();
+    void createImageBufferInternal(PassOwnPtr<ImageBufferSurface> externalSurface);
     bool shouldUseDisplayList(const IntSize& deviceSize);
 
     void setSurfaceSize(const IntSize&);
 
     bool paintsIntoCanvasBuffer() const;
 
     void updateExternallyAllocatedMemory() const;
 
     String toDataURLInternal(const String& mimeType, const double* quality, SourceDrawingBuffer) const;
 
@@ skipping 17 matching lines @@
     bool m_imageBufferIsClear;
     OwnPtr<ImageBuffer> m_imageBuffer;
     mutable OwnPtr<GraphicsContextStateSaver> m_contextStateSaver;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h