Cleanup: Pass std::string as const reference if possible

sync/internal_api/sync_manager_factory.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 "sync/internal_api/public/sync_manager_factory.h"
 
 #include "sync/internal_api/sync_backup_manager.h"
 #include "sync/internal_api/sync_manager_impl.h"
 #include "sync/internal_api/sync_rollback_manager.h"
 
 namespace syncer {
 
 SyncManagerFactory::SyncManagerFactory(SyncManagerFactory::MANAGER_TYPE type)
     : type_(type) {
 }
 
 SyncManagerFactory::~SyncManagerFactory() {
 }
 
 scoped_ptr<SyncManager> SyncManagerFactory::CreateSyncManager(
-      const std::string name) {
+    const std::string& name) {
   switch (type_) {
     case NORMAL:
       return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
     case BACKUP:
       return scoped_ptr<SyncManager>(new SyncBackupManager());
     case ROLLBACK:
       return scoped_ptr<SyncManager>(new SyncRollbackManager());
     default:
       NOTREACHED();
       return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
   }
 }
 
 }  // namespace syncer