Fix memory leak in PrerenderDispatcher.

chrome/renderer/prerender/prerender_dispatcher.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_RENDERER_PRERENDER_PRERENDER_DISPATCHER_H_
 #define CHROME_RENDERER_PRERENDER_PRERENDER_DISPATCHER_H_
 #pragma once
 
 #include <map>
 
 #include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
 #include "content/public/renderer/render_process_observer.h"
 
 class GURL;
 
 namespace prerender {
 
+class PrerenderingSupport;
+
 // PrerenderDispatcher keeps track of which URLs are being prerendered. There
 // is only one PrerenderDispatcher per render process, and it will only be
-// aware of prerenders that are triggered by this render process.
+// aware of prerenders that are triggered by this render process.  As well,
+// it holds on to other objects that must exist once per-renderer process,
+// such as the PrerenderingSupport.
 class PrerenderDispatcher : public content::RenderProcessObserver {
  public:
   PrerenderDispatcher();
   virtual ~PrerenderDispatcher();
 
   bool IsPrerenderURL(const GURL & url) const;
 
  private:
   void OnAddPrerenderURL(const GURL& url);
   void OnRemovePrerenderURL(const GURL& url);
 
   // RenderProcessObserver:
   virtual bool OnControlMessageReceived(const IPC::Message& message) OVERRIDE;
 
   typedef std::map<GURL, int> PrerenderMap;
   PrerenderMap prerender_urls_;
+
+  // There is one PrerenderingSupport object per renderer, and it provides
+  // the interface to prerendering to the WebKit platform.
+  scoped_ptr<PrerenderingSupport> prerendering_support_;
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_RENDERER_PRERENDER_PRERENDER_DISPATCHER_H_