Re-enable TopSites in PrerenderManager, this time duplicating the invariant

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 186 matching lines @@
                          FinalStatus final_status) const;
 
   const Config& config() const { return config_; }
   Config& mutable_config() { return config_; }
 
   PrerenderTracker* prerender_tracker() { return prerender_tracker_; }
 
   // Adds a condition. This is owned by the PrerenderManager.
   void AddCondition(const PrerenderCondition* condition);
 
-  bool IsTopSite(const GURL& url) const;
+  bool IsTopSite(const GURL& url);
 
  protected:
   // Test that needs needs access to internal functions.
   FRIEND_TEST_ALL_PREFIXES(PrerenderManagerTest, ExpireTest);
   FRIEND_TEST_ALL_PREFIXES(PrerenderManagerTest, ExtractURLInQueryStringTest);
 
   struct PendingContentsData;
 
   void SetPrerenderContentsFactory(
       PrerenderContents::Factory* prerender_contents_factory);
@@ skipping 177 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_