Cleanup: Pass std::string as const reference from content/

content/browser/renderer_host/p2p/socket_host_test_utils.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_P2P_SOCKET_HOST_TEST_UTILS_H_
 #define CONTENT_BROWSER_RENDERER_HOST_P2P_SOCKET_HOST_TEST_UTILS_H_
 
 #include <vector>
 
 #include "content/common/p2p_messages.h"
@@ skipping 77 matching lines @@
   net::IPEndPoint local_address_;
 
   net::BoundNetLog net_log_;
 };
 
 void CreateRandomPacket(std::vector<char>* packet);
 void CreateStunRequest(std::vector<char>* packet);
 void CreateStunResponse(std::vector<char>* packet);
 void CreateStunError(std::vector<char>* packet);
 
-net::IPEndPoint ParseAddress(const std::string ip_str, uint16 port);
+net::IPEndPoint ParseAddress(const std::string& ip_str, uint16 port);
 
 MATCHER_P(MatchMessage, type, "") {
   return arg->type() == type;
 }
 
 MATCHER_P(MatchPacketMessage, packet_content, "") {
   if (arg->type() != P2PMsg_OnDataReceived::ID)
     return false;
   P2PMsg_OnDataReceived::Param params;
   P2PMsg_OnDataReceived::Read(arg, &params);
   return base::get<2>(params) == packet_content;
 }
 
 MATCHER_P(MatchIncomingSocketMessage, address, "") {
   if (arg->type() != P2PMsg_OnIncomingTcpConnection::ID)
     return false;
   P2PMsg_OnIncomingTcpConnection::Param params;
   P2PMsg_OnIncomingTcpConnection::Read(
       arg, &params);
   return base::get<1>(params) == address;
 }
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_P2P_SOCKET_HOST_TEST_UTILS_H_