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

net/tools/quic/test_tools/quic_test_client.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 "net/tools/quic/test_tools/quic_test_client.h"
 
 #include "base/time/time.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_errors.h"
 #include "net/cert/cert_verify_result.h"
@@ skipping 300 matching lines @@
 
   scoped_ptr<BalsaHeaders> munged_headers(MungeHeaders(message.headers(),
                                           secure_));
   ssize_t ret = GetOrCreateStreamAndSendRequest(
       (munged_headers.get() ? munged_headers.get() : message.headers()),
       message.body(), message.has_complete_message(), nullptr);
   WaitForWriteToFlush();
   return ret;
 }
 
-ssize_t QuicTestClient::SendData(string data, bool last_data) {
+ssize_t QuicTestClient::SendData(const string& data, bool last_data) {
   return SendData(data, last_data, nullptr);
 }
 
-ssize_t QuicTestClient::SendData(string data,
+ssize_t QuicTestClient::SendData(const string& data,
                                  bool last_data,
                                  QuicAckNotifier::DelegateInterface* delegate) {
   return GetOrCreateStreamAndSendRequest(nullptr, StringPiece(data), last_data,
                                          delegate);
 }
 
 bool QuicTestClient::response_complete() const {
   return response_complete_;
 }
 
@@ skipping 305 matching lines @@
   message->headers()->SetRequestVersion(
       HTTPMessage::VersionToString(HttpConstants::HTTP_1_1));
   message->headers()->SetRequestMethod(
       HTTPMessage::MethodToString(HttpConstants::GET));
   message->headers()->SetRequestUri(uri);
 }
 
 }  // namespace test
 }  // namespace tools
 }  // namespace net