Detach all subframes before swapping a frame.

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 97 matching lines @@
     typedef unsigned RenderAsTextControls;
 
     // Returns the number of live WebFrame objects, used for leak checking.
     BLINK_EXPORT static int instanceCount();
 
     virtual bool isWebLocalFrame() const = 0;
     virtual WebLocalFrame* toWebLocalFrame() = 0;
     virtual bool isWebRemoteFrame() const = 0;
     virtual WebRemoteFrame* toWebRemoteFrame() = 0;
 
-    BLINK_EXPORT void swap(WebFrame*);
+    BLINK_EXPORT bool swap(WebFrame*);
 
     // This method closes and deletes the WebFrame.
     virtual void close() = 0;
 
 
     // Basic properties ---------------------------------------------------
 
     // The unique name of this frame.
     virtual WebString uniqueName() const = 0;
 
@@ skipping 573 matching lines @@
     WebPrivateOwnPtr<OpenedFrameTracker> m_openedFrameTracker;
 };
 
 #if BLINK_IMPLEMENTATION
 Frame* toCoreFrame(const WebFrame*);
 #endif
 
 } // namespace blink
 
 #endif