Coverity: Pass parameters by reference.

chrome/browser/sync/glue/session_model_associator.cc

 // 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.
 
 #include "chrome/browser/sync/glue/session_model_associator.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/string_util.h"
@@ skipping 81 matching lines @@
     int64* sync_id) {
   sync_api::ReadTransaction trans(
       sync_service_->backend()->GetUserShareHandle());
   sync_api::ReadNode node(&trans);
   if (!node.InitByClientTagLookup(syncable::SESSIONS, *tag))
     return false;
   *sync_id = node.GetId();
   return true;
 }
 
-int64 SessionModelAssociator::GetSyncIdFromChromeId(std::string id) {
+int64 SessionModelAssociator::GetSyncIdFromChromeId(const std::string& id) {
   sync_api::ReadTransaction trans(
       sync_service_->backend()->GetUserShareHandle());
   sync_api::ReadNode node(&trans);
   if (!node.InitByClientTagLookup(syncable::SESSIONS, id))
     return sync_api::kInvalidId;
   return node.GetId();
 }
 
 bool SessionModelAssociator::SyncModelHasUserCreatedNodes(bool* has_nodes) {
   DCHECK(CalledOnValidThread());
@@ skipping 450 matching lines @@
       return false;
     }
     create_node.SetSessionSpecifics(*session_data);
     return true;
   }
   write_node.SetSessionSpecifics(*session_data);
   return true;
 }
 
 }  // namespace browser_sync