Add Blink APIs for frame tree mirroring.

Source/core/html/HTMLFrameOwnerElement.h

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  *
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 21 matching lines @@
 class Frame;
 class RenderPart;
 class Widget;
 
 class HTMLFrameOwnerElement : public HTMLElement, public FrameOwner {
 public:
     virtual ~HTMLFrameOwnerElement();
 
     // FrameOwner overrides:
     virtual bool isLocal() const { return true; }
+    virtual void setContentFrame(Frame&) OVERRIDE;
+    virtual void clearContentFrame() OVERRIDE;

[abarth-chromium, 2014/06/13 18:06:46]

This can still be private.  That will force callers to use FrameOwner's
interface.

[dcheng, 2014/06/13 23:56:12]

Done.

     virtual SandboxFlags sandboxFlags() const OVERRIDE { return m_sandboxFlags; }
     virtual void dispatchLoad() OVERRIDE;
 
     Frame* contentFrame() const { return m_contentFrame; }
     DOMWindow* contentWindow() const;
     Document* contentDocument() const;
 
-    void setContentFrame(Frame&);
-    void clearContentFrame();
-
     void disconnectContentFrame();
 
     // Most subclasses use RenderPart (either RenderEmbeddedObject or RenderIFrame)
     // except for HTMLObjectElement and HTMLEmbedElement which may return any
     // RenderObject when using fallback content.
     RenderPart* renderPart() const;
 
     Document* getSVGDocument(ExceptionState&) const;
 
     virtual ScrollbarMode scrollingMode() const { return ScrollbarAuto; }
@@ skipping 65 matching lines @@
     }
 
     Node& m_root;
 };
 
 DEFINE_TYPE_CASTS(HTMLFrameOwnerElement, FrameOwner, owner, owner->isLocal(), owner.isLocal());
 
 } // namespace WebCore
 
 #endif // HTMLFrameOwnerElement_h