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

sync/internal_api/public/sync_manager_factory.h

 // Copyright 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 SYNC_INTERNAL_API_PUBLIC_SYNC_MANAGER_FACTORY_H_
 #define SYNC_INTERNAL_API_PUBLIC_SYNC_MANAGER_FACTORY_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "sync/base/sync_export.h"
 
 namespace syncer {
 
 class SyncManager;
 
 // Helper class to allow dependency injection of the SyncManager.
 class SYNC_EXPORT SyncManagerFactory {
  public:
   enum MANAGER_TYPE {
     NORMAL,     // Normal sync manager
     BACKUP,     // Backup sync manager
     ROLLBACK,   // Rollback sync manager
   };
 
   SyncManagerFactory(MANAGER_TYPE type);
   virtual ~SyncManagerFactory();
 
-  virtual scoped_ptr<SyncManager> CreateSyncManager(std::string name);
+  virtual scoped_ptr<SyncManager> CreateSyncManager(const std::string& name);
 
  private:
   MANAGER_TYPE type_;
   DISALLOW_COPY_AND_ASSIGN(SyncManagerFactory);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_SYNC_MANAGER_FACTORY_H_