[Coverity] Pass-by-val -> pass-by-ref

chrome/browser/extensions/web_intent_callbacks.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_BROWSER_EXTENSIONS_WEB_INTENT_CALLBACKS_H_
 #define CHROME_BROWSER_EXTENSIONS_WEB_INTENT_CALLBACKS_H_
 
 #include "base/memory/singleton.h"
 #include "chrome/browser/profiles/profile_keyed_service.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
@@ skipping 50 matching lines @@
     virtual ~Factory();
 
     // ProfileKeyedServiceFactory
     virtual ProfileKeyedService* BuildServiceInstanceFor(
         Profile* profile) const OVERRIDE;
   };
 
   // Private method to get and clear the dispatcher for the given string key.
   // If there is no dispatcher available, this will return NULL. Otherwise, this
   // transfers ownership of the WebIntentsDispatcher to the caller.
-  content::WebIntentsDispatcher* GetAndClear(std::string key);
+  content::WebIntentsDispatcher* GetAndClear(const std::string& key);
 
   class SourceObserver;
 
   // Used as an incrementing ID for callback keys.
   int last_id_;
 
   // Stores all pending callbacks sent to platform apps.
   CallbackMap pending_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_WEB_INTENT_CALLBACKS_H_