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

Source/core/rendering/HitTestResult.cpp

Index: Source/core/rendering/HitTestResult.cpp
diff --git a/Source/core/rendering/HitTestResult.cpp b/Source/core/rendering/HitTestResult.cpp
index 63f71c09e4fceeb2b6fd70a57a1efe9393783ba1..bb15cef9a3d506d89bf8a989e6013c76154f7138 100644
--- a/Source/core/rendering/HitTestResult.cpp
+++ b/Source/core/rendering/HitTestResult.cpp
@@ -283,7 +283,8 @@ KURL HitTestResult::absoluteImageURL() const
         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)