Use ChildFrameDisconnector when detaching child frames of a LocalFrame.

third_party/WebKit/Source/core/frame/LocalFrame.h

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999-2001 Lars Knoll <knoll@kde.org>
  *                     1999-2001 Antti Koivisto <koivisto@kde.org>
  *                     2000-2001 Simon Hausmann <hausmann@kde.org>
  *                     2000-2001 Dirk Mueller <mueller@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
@@ skipping 88 matching lines @@
     void navigate(Document& originDocument, const KURL&, bool replaceCurrentItem, UserGestureStatus) override;
     void navigate(const FrameLoadRequest&) override;
     void reload(FrameLoadType, ClientRedirectPolicy) override;
     void detach(FrameDetachType) override;
     bool shouldClose() override;
     SecurityContext* securityContext() const override;
     void printNavigationErrorMessage(const Frame&, const char* reason) override;
     bool prepareForCommit() override;
     void didChangeVisibilityState() override;
 
+    void detachChildren();
+
     LocalDOMWindow* localDOMWindow() const;
     void setDOMWindow(LocalDOMWindow*);
     FrameView* view() const;
     Document* document() const;
     void setPagePopupOwner(Element&);
     Element* pagePopupOwner() const { return m_pagePopupOwner.get(); }
 
     LayoutView* contentLayoutObject() const; // Root of the layout tree for the document contained in this frame.
     LayoutViewItem contentLayoutItem() const;
 
@@ skipping 215 matching lines @@
     explicit ScopedFrameBlamer(LocalFrame*);
     ~ScopedFrameBlamer();
 
 private:
     Member<LocalFrame> m_frame;
 };
 
 } // namespace blink
 
 #endif // LocalFrame_h