Set default document urls to 'about:blank'.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 1282 matching lines @@
 
   const PropertyRegistry* propertyRegistry() const;
   PropertyRegistry* propertyRegistry();
 
   // Document maintains a counter of visible non-secure password
   // fields in the page. Used to notify the embedder when all visible
   // non-secure passwords fields are no longer visible.
   void incrementPasswordCount();
   void decrementPasswordCount();
 
+  // Set the default Document URLs to about:blank.
+  KURL urlForBinding() {

[tkent, 2017/03/20 23:06:54]

Let's declare urlForBinding() around url(), and add comments to both of url()
and urlForBinding() to explain their differences.

Also, move the function definition to Document.cpp.  We want to avoid inline
function definitions if it's not just one expression.

+    if (!url().isNull()) {
+      return url();
+    }
+    return blankURL();
+  }
+
  protected:
   Document(const DocumentInit&, DocumentClassFlags = DefaultDocumentClass);
 
   void didUpdateSecurityOrigin() final;
 
   void clearXMLVersion() { m_xmlVersion = String(); }
 
   virtual Document* cloneDocumentWithoutChildren();
 
   bool importContainerNodeChildren(ContainerNode* oldContainerNode,
@@ skipping 398 matching lines @@
 DEFINE_TYPE_CASTS(TreeScope, Document, document, true, true);
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 CORE_EXPORT void showLiveDocumentInstances();
 #endif
 
 #endif  // Document_h