Coverity: Pass parameters by reference.

chrome/browser/sync/glue/preference_model_associator.h

 // Copyright (c) 2010 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_SYNC_GLUE_PREFERENCE_MODEL_ASSOCIATOR_H_
 #define CHROME_BROWSER_SYNC_GLUE_PREFERENCE_MODEL_ASSOCIATOR_H_
 #pragma once
 
 #include <map>
 #include <set>
@@ skipping 58 matching lines @@
     // thread.
   }
 
   // Not implemented.
   virtual const PrefService::Preference* GetChromeNodeFromSyncId(
       int64 sync_id) {
     return NULL;
   }
 
   // Not implemented.
-  virtual bool InitSyncNodeFromChromeId(std::string node_id,
+  virtual bool InitSyncNodeFromChromeId(const std::string& node_id,
                                         sync_api::BaseNode* sync_node) {
     return false;
   }
 
   // Returns the sync id for the given preference name, or sync_api::kInvalidId
   // if the preference name is not associated to any sync id.
-  virtual int64 GetSyncIdFromChromeId(std::string node_id);
+  virtual int64 GetSyncIdFromChromeId(const std::string& node_id);
 
   // Associates the given preference name with the given sync id.
   virtual void Associate(const PrefService::Preference* node, int64 sync_id);
 
   // Remove the association that corresponds to the given sync id.
   virtual void Disassociate(int64 sync_id);
 
   // Returns whether a node with the given permanent tag was found and update
   // |sync_id| with that node's id.
   virtual bool GetSyncIdForTaggedNode(const std::string& tag, int64* sync_id);
@@ skipping 35 matching lines @@
 
   PreferenceNameToSyncIdMap id_map_;
   SyncIdToPreferenceNameMap id_map_inverse_;
 
   DISALLOW_COPY_AND_ASSIGN(PreferenceModelAssociator);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_PREFERENCE_MODEL_ASSOCIATOR_H_