Implement "Save image as" for canvas (blink side).

Source/core/rendering/HitTestResult.cpp

 /*
  * Copyright (C) 2006, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 265 matching lines @@
 
 KURL HitTestResult::absoluteImageURL() const
 {
     if (!m_innerNonSharedNode)
         return KURL();
 
     if (!(m_innerNonSharedNode->renderer() && m_innerNonSharedNode->renderer()->isImage()))
         return KURL();
 
     AtomicString urlString;
-    if (isHTMLEmbedElement(*m_innerNonSharedNode)
+    if (isHTMLCanvasElement(*m_innerNonSharedNode)

[Justin Novosad, 2014/04/24 14:19:39]

This may work, but it is way too cumbersome. It implies generating a potentially
massive data URL just for querying the hit test result.  This can cause a delay
in displaying the contextual menu.  Also, there is no requirement to offer all
the same menu options as we do for image media.  The only options that make
sense in my opinion are "Save Image As" and "Copy Image".  We should not be
offering to copy the image location or to open in a new tab.

+        || isHTMLEmbedElement(*m_innerNonSharedNode)
         || isHTMLImageElement(*m_innerNonSharedNode)
         || isHTMLInputElement(*m_innerNonSharedNode)
         || isHTMLObjectElement(*m_innerNonSharedNode)
         || isSVGImageElement(*m_innerNonSharedNode)
        ) {
         urlString = toElement(*m_innerNonSharedNode).imageSourceURL();
     } else
         return KURL();
 
     return m_innerNonSharedNode->document().completeURL(stripLeadingAndTrailingHTMLSpaces(urlString));
@@ skipping 188 matching lines @@
 {
     for (Node* node = m_innerNode.get(); node; node = NodeRenderingTraversal::parent(node)) {
         if (node->isElementNode())
             return toElement(node);
     }
 
     return 0;
 }
 
 } // namespace WebCore