base: Remove non-const refs from the MRUCache implementation.

chrome/browser/ui/app_list/search/common/webservice_cache.h

 // Copyright 2013 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_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_
 #define CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_
 
 #include <utility>
 
 #include "base/basictypes.h"
@@ skipping 57 matching lines @@
             const base::DictionaryValue* result)
         : time(time), result(result) {}
     Payload() {}
 
     base::Time time;
     const base::DictionaryValue* result;
   };
 
   class CacheDeletor {
    public:
-    void operator()(Payload& payload);
+    void operator()(const Payload& payload);
   };
   typedef base::MRUCacheBase<std::string, Payload, CacheDeletor> Cache;
 
   // Callback for when the cache is loaded from the dictionary data store.
   void OnCacheLoaded(scoped_ptr<base::DictionaryValue>);
 
   // Populates the payload parameter with the corresponding payload stored
   // in the given dictionary. If the dictionary is invalid for any reason,
   // this method will return false.
   bool PayloadFromDict(const base::DictionaryValue* dict,
@@ skipping 15 matching lines @@
   scoped_refptr<DictionaryDataStore> data_store_;
 
   bool cache_loaded_;
 
   DISALLOW_COPY_AND_ASSIGN(WebserviceCache);
 };
 
 }  // namespace app_list
 
 #endif  // CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_