Add Blink APIs for frame tree mirroring.

Source/web/WebRemoteFrameImpl.h

Index: Source/web/WebRemoteFrameImpl.h
diff --git a/Source/web/WebRemoteFrameImpl.h b/Source/web/WebRemoteFrameImpl.h
index ffa739dc372d10270f4e754ac4c2f4115aa3fca5..184137a63bdbee6afb2e213ed7edce1be4701d68 100644
--- a/Source/web/WebRemoteFrameImpl.h
+++ b/Source/web/WebRemoteFrameImpl.h
@@ -43,6 +43,7 @@ public:
     virtual bool hasHorizontalScrollbar() const OVERRIDE;
     virtual bool hasVerticalScrollbar() const OVERRIDE;
     virtual WebView* view() const OVERRIDE;
+    virtual void initializeAsMainFrame(WebView*) OVERRIDE;
     virtual WebFrame* traversePrevious(bool wrap) const OVERRIDE;
     virtual WebFrame* traverseNext(bool wrap) const OVERRIDE;
     virtual WebFrame* findChildByName(const WebString&) const OVERRIDE;
@@ -170,6 +171,10 @@ public:
     virtual bool selectionStartHasSpellingMarkerFor(int from, int length) const OVERRIDE;
     virtual WebString layerTreeAsText(bool showDebugInfo = false) const OVERRIDE;
 
+    virtual WebLocalFrame* createLocalChild(const WebString& name, WebFrameClient*) OVERRIDE;
+    virtual WebRemoteFrame* createRemoteChild(const WebString& name, WebFrameClient*) OVERRIDE;
+
+    void setWebCoreFrame(PassRefPtr<WebCore::RemoteFrame>);
     WebCore::RemoteFrame* frame() const { return m_frame.get(); }
 
 private: