Strip away base::RefCountedThreadSafe use from PrerenderManager

chrome/browser/prerender/prerender_manager.h

 // Copyright (c) 2011 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_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 #pragma once
 
 #include <list>
 #include <map>
@@ skipping 204 matching lines @@
 
   void SetPrerenderContentsFactory(
       PrerenderContents::Factory* prerender_contents_factory);
 
   PendingContentsData* FindPendingEntry(const GURL& url);
 
  private:
   // Test that needs needs access to internal functions.
   friend class PrerenderBrowserTest;
 
-  friend class base::RefCountedThreadSafe<PrerenderManager>;
-
   struct PrerenderContentsData;
   struct NavigationRecord;
 
   class OnCloseTabContentsDeleter;
 
   class MostVisitedSites;
 
   // Adds a prerender for |url| from referrer |referrer| initiated from the
   // RenderViewHost specified by |child_route_id_pair|. The |origin| specifies
   // how the prerender was added.
@@ skipping 158 matching lines @@
   scoped_ptr<PrerenderHistograms> histograms_;
 
   scoped_ptr<MostVisitedSites> most_visited_;
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderManager);
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_