Move the Widget hierarchy to the Oilpan heap.

Source/web/FrameLoaderClientImpl.h

 /*
  * Copyright (C) 2009, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple 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.
@@ skipping 104 matching lines @@
     virtual PassRefPtr<DocumentLoader> createDocumentLoader(LocalFrame*, const ResourceRequest&, const SubstituteData&) override;
     virtual WTF::String userAgent(const KURL&) override;
     virtual WTF::String doNotTrackValue() override;
     virtual void transitionToCommittedForNewPage() override;
     virtual PassRefPtrWillBeRawPtr<LocalFrame> createFrame(const KURL&, const WTF::AtomicString& name, HTMLFrameOwnerElement*) override;
     virtual bool canCreatePluginWithoutRenderer(const String& mimeType) const;
     virtual PassOwnPtrWillBeRawPtr<PluginPlaceholder> createPluginPlaceholder(
         Document&, const KURL&,
         const Vector<String>& paramNames, const Vector<String>& paramValues,
         const String& mimeType, bool loadManually) override;
-    virtual PassRefPtr<Widget> createPlugin(
+    virtual PassRefPtrWillBeRawPtr<Widget> createPlugin(
         HTMLPlugInElement*, const KURL&,
         const Vector<WTF::String>&, const Vector<WTF::String>&,
         const WTF::String&, bool loadManually, DetachedPluginPolicy) override;
-    virtual PassRefPtr<Widget> createJavaAppletWidget(
+    virtual PassRefPtrWillBeRawPtr<Widget> createJavaAppletWidget(
         HTMLAppletElement*,
         const KURL& /* base_url */,
         const Vector<WTF::String>& paramNames,
         const Vector<WTF::String>& paramValues) override;
     virtual ObjectContentType objectContentType(
         const KURL&, const WTF::String& mimeType, bool shouldPreferPlugInsForImages) override;
     virtual void didChangeScrollOffset() override;
     virtual void didUpdateCurrentHistoryItem() override;
     virtual void didRemoveAllPendingStylesheet() override;
     virtual bool allowScript(bool enabledPerSettings) override;
@@ skipping 40 matching lines @@
     // The WebFrame that owns this object and manages its lifetime. Therefore,
     // the web frame object is guaranteed to exist.
     WebLocalFrameImpl* m_webFrame;
 };
 
 DEFINE_TYPE_CASTS(FrameLoaderClientImpl, FrameLoaderClient, client, client->isFrameLoaderClientImpl(), client.isFrameLoaderClientImpl());
 
 } // namespace blink
 
 #endif