Have MessagePort use Oilpan-based weak pointers.

third_party/WebKit/Source/core/html/FormAssociatedElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef FormAssociatedElement_h
 #define FormAssociatedElement_h
 
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
-#include "wtf/WeakPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class ContainerNode;
 class Document;
 class FormAttributeTargetObserver;
 class FormData;
 class HTMLElement;
 class HTMLFormElement;
@@ skipping 85 matching lines @@
 };
 
 CORE_EXPORT HTMLElement* toHTMLElement(FormAssociatedElement*);
 CORE_EXPORT HTMLElement& toHTMLElement(FormAssociatedElement&);
 CORE_EXPORT const HTMLElement* toHTMLElement(const FormAssociatedElement*);
 CORE_EXPORT const HTMLElement& toHTMLElement(const FormAssociatedElement&);
 
 } // namespace blink
 
 #endif // FormAssociatedElement_h