Refactoring source image usage in CanvasRenderingContext2D

Source/core/html/HTMLCanvasElement.h

Index: Source/core/html/HTMLCanvasElement.h
diff --git a/Source/core/html/HTMLCanvasElement.h b/Source/core/html/HTMLCanvasElement.h
index 88ab866e8a51534575039c07b19336efe0dfe468..31bc0f8251537655f576973b393430033bda244e 100644
--- a/Source/core/html/HTMLCanvasElement.h
+++ b/Source/core/html/HTMLCanvasElement.h
@@ -29,6 +29,7 @@
 #define HTMLCanvasElement_h
 
 #include "core/html/HTMLElement.h"
+#include "core/html/canvas/CanvasImageSource.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/Canvas2DLayerBridge.h"
@@ -59,7 +60,7 @@ public:
     virtual void canvasDestroyed(HTMLCanvasElement*) = 0;
 };
 
-class HTMLCanvasElement FINAL : public HTMLElement, public DocumentVisibilityObserver {
+class HTMLCanvasElement FINAL : public HTMLElement, public DocumentVisibilityObserver, public CanvasImageSource {
 public:
     static PassRefPtr<HTMLCanvasElement> create(Document&);
     virtual ~HTMLCanvasElement();
@@ -116,7 +117,7 @@ public:
 
     SecurityOrigin* securityOrigin() const;
     void setOriginTainted() { m_originClean = false; }
-    bool originClean() const { return m_originClean; }
+    virtual bool originClean() const { return m_originClean; }
 
     AffineTransform baseTransform() const;
 
@@ -131,6 +132,11 @@ public:
     // DocumentVisibilityObserver implementation
     virtual void didChangeVisibilityState(PageVisibilityState) OVERRIDE;
 
+    // CanvasImageSource implementation
+    virtual PassRefPtr<Image> getSourceImageForCanvas(HTMLCanvasElement*, ExceptionState&, CanvasImageSourceUsage, bool* isVolatile) const OVERRIDE;
+    virtual bool wouldTaintOrigin(CanvasRenderingContext* destination) const OVERRIDE;
+    virtual FloatSize sourceSize() const OVERRIDE;
+
 protected:
     virtual void didMoveToNewDocument(Document& oldDocument) OVERRIDE;