Add Blink APIs for frame tree mirroring.

public/web/WebFrame.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 183 matching lines @@
     // Returns the frame that opened this frame or 0 if there is none.
     BLINK_EXPORT WebFrame* opener() const;
 
     // Sets the frame that opened this one or 0 if there is none.
     virtual void setOpener(WebFrame*);
 
     // Reset the frame that opened this frame to 0.
     // This is executed between layout tests runs
     void clearOpener() { setOpener(0); }
 
+    // Called by the WebView to initialize the main frame for the page.
+    virtual void initializeAsMainFrame(WebView*) = 0;

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

Why is this API public?  If it's called by the WebView, it can be private,
right?

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

I'd like to avoid friending WebViewImpl if possible--it seems a bit out of place
here.

How would you feel about de-virtualizing this, and updating
WebViewImpl::setMainFrame to dispatch like this:
    if (f->isLocal())
        toWebLocalFrameImpl(f)->initializeAsMainFrame(page());
    else
        toWebRemoteFrameImpl(f)->initializeAsMainFrame(page());

+
     // Adds the given frame as a child of this frame.
     virtual void appendChild(WebFrame*);
 
     // Removes the given child from this frame.
     virtual void removeChild(WebFrame*);
 
     // Returns the parent frame or 0 if this is a top-most frame.
     BLINK_EXPORT WebFrame* parent() const;
 
     // Returns the top-most frame in the hierarchy containing this frame.
@@ skipping 480 matching lines @@
     WebPrivateOwnPtr<OpenedFrameTracker> m_openedFrameTracker;
 };
 
 #if BLINK_IMPLEMENTATION
 WebCore::Frame* toWebCoreFrame(WebFrame*);
 #endif
 
 } // namespace blink
 
 #endif