Make CanvasRenderingContext not inherit from ActiveDOMObject

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 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 919 matching lines @@
 AffineTransform HTMLCanvasElement::baseTransform() const
 {
     ASSERT(hasImageBuffer() && !m_didFailToCreateImageBuffer);
     return m_imageBuffer->baseTransform();
 }
 
 void HTMLCanvasElement::didChangeVisibilityState(PageVisibilityState visibility)
 {
     if (!m_context)
         return;
+
     bool hidden = visibility != PageVisibilityStateVisible;
     m_context->setIsHidden(hidden);
     if (hidden) {
         clearCopiedImage();
         if (is3D()) {
             discardImageBuffer();
         }
     }
 }
 
+void HTMLCanvasElement::willDetachDocument()
+{
+    if (m_context)
+        m_context->stop();
+}
+
 void HTMLCanvasElement::styleDidChange(const ComputedStyle* oldStyle, const ComputedStyle& newStyle)
 {
     if (m_context)
         m_context->styleDidChange(oldStyle, newStyle);
 }
 
 void HTMLCanvasElement::didMoveToNewDocument(Document& oldDocument)
 {
     setObservedDocument(document());
-    if (m_context)
-        m_context->didMoveToNewDocument(&document());
     HTMLElement::didMoveToNewDocument(oldDocument);
 }
 
 PassRefPtr<Image> HTMLCanvasElement::getSourceImageForCanvas(SourceImageStatus* status, AccelerationHint hint) const
 {
     if (!width() || !height()) {
         *status = ZeroSizeCanvasSourceImageStatus;
         return nullptr;
     }
 
@@ skipping 45 matching lines @@
     }
     return ImageBitmapSource::fulfillImageBitmap(scriptState, isPaintable() ? ImageBitmap::create(this, IntRect(sx, sy, sw, sh), options) : nullptr);
 }
 
 bool HTMLCanvasElement::isOpaque() const
 {
     return m_context && !m_context->hasAlpha();
 }
 
 } // namespace blink