Set default document urls to 'about:blank'.

third_party/WebKit/Source/core/dom/Document.h

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index ea9df469f02ccd75c7b6316efdc13354607fdc46..d1b6a34ec474491bfe57b4010821a1c43799e9eb 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -595,9 +595,13 @@ class CORE_EXPORT Document : public ContainerNode,
 
   bool wellFormed() const { return m_wellFormed; }
 
+  // Get the URL that was used to retrieve this document.

[tkent, 2017/03/22 08:36:27]

We are not sure if we should remove it or not. So past tense isn't reasonable.
Also, this comment doesn't explain difference from urlForBinding().
How about something like:

// Return the document URL, or an empty URL if it's unavailable.
// This is not an implementation of web-exposed Document.prototype.URL.

   const KURL& url() const { return m_url; }
   void setURL(const KURL&);
 
+  // Bind the url to document.url, if unavailable bind to about:blank.
+  KURL urlForBinding();
+
   // To understand how these concepts relate to one another, please see the
   // comments surrounding their declaration.
   const KURL& baseURL() const { return m_baseURL; }