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

chrome/browser/extensions/web_intent_callbacks.cc

 // 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.
 
 #include "base/stringprintf.h"
 #include "chrome/browser/extensions/web_intent_callbacks.h"
 #include "chrome/browser/profiles/profile_dependency_manager.h"
 #include "chrome/common/extensions/extension.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
@@ skipping 10 matching lines @@
 
 namespace extensions {
 
 // SourceObserver is a subclass of WebContentsObserver that is instantiated
 // on RegisterCallback to wait for the source WebContents to be destroyed.
 // If it is destroyed, this automatically clears the callback from pending_.
 class WebIntentCallbacks::SourceObserver : content::WebContentsObserver {
  public:
   SourceObserver(content::WebContents* web_contents,
                  WebIntentCallbacks* callbacks,
-                 const std::string key)
+                 const std::string& key)
       : content::WebContentsObserver(web_contents),
         callbacks_(callbacks),
         key_(key) {}
   virtual ~SourceObserver() {}
 
   // Implement WebContentsObserver
   virtual void WebContentsDestroyed(content::WebContents* web_contents)
       OVERRIDE {
     content::WebIntentsDispatcher* dispatcher =
         callbacks_->GetAndClear(key_);
@@ skipping 40 matching lines @@
   return id;
 }
 
 content::WebIntentsDispatcher* WebIntentCallbacks::RetrieveCallback(
     const Extension* extension, int id) {
   std::string key = GetKey(extension, id);
   return GetAndClear(key);
 }
 
 content::WebIntentsDispatcher* WebIntentCallbacks::GetAndClear(
-    std::string key) {
+    const std::string& key) {
   if (!pending_.count(key))
     return NULL;
 
   content::WebIntentsDispatcher* dispatcher = pending_[key];
   pending_.erase(key);
   return dispatcher;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Factory boilerplate
@@ skipping 16 matching lines @@
 
 WebIntentCallbacks::Factory::~Factory() {
 }
 
 ProfileKeyedService* WebIntentCallbacks::Factory::BuildServiceInstanceFor(
     Profile* profile) const {
   return new WebIntentCallbacks();
 }
 
 }  // namespace extensions