Convert JsonWriter::Write to taking a const ref for the in-param

sync/test/accounts_client/test_accounts_client_unittest.cc

 // Copyright 2013 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 <vector>
 
 #include "base/json/json_writer.h"
 #include "base/values.h"
 #include "sync/test/accounts_client/test_accounts_client.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ skipping 49 matching lines @@
   usernames.push_back("foo2@gmail.com");
   NoNetworkTestAccountsClient client(kServer, kAccountSpace, usernames);
 
   base::DictionaryValue success_dict;
   success_dict.Set("username", new base::StringValue(kUsername));
   success_dict.Set("account_space", new base::StringValue(kAccountSpace));
   success_dict.Set("session_id", new base::StringValue(kSessionId));
   success_dict.Set("expiration_time", new base::StringValue(kExpirationTime));
 
   string success_response;
-  base::JSONWriter::Write(&success_dict, &success_response);
+  base::JSONWriter::Write(success_dict, &success_response);
   EXPECT_CALL(client, SendRequest(_, _))
       .WillOnce(DoAll(SetArgPointee<1>(success_response), Return(true)));
 
   AccountSession session;
   EXPECT_TRUE(client.ClaimAccount(&session));
   EXPECT_EQ(kUsername, session.username);
   EXPECT_EQ(kAccountSpace, session.account_space);
   EXPECT_EQ(kSessionId, session.session_id);
   EXPECT_EQ(kExpirationTime, session.expiration_time);
 }
 
 TEST(TestAccountsClientTest, ReleaseAccountEmptySession) {
   vector<string> usernames;
   NoNetworkTestAccountsClient client(kServer, kAccountSpace, usernames);
   AccountSession session;
   // No expectation for SendRequest is made because no network call should be
   // performed in this scenario.
   client.ReleaseAccount(session);
 }
 
 TEST(TestAccountsClientTest, ReleaseAccountSuccess) {
   vector<string> usernames;
   NoNetworkTestAccountsClient client(kServer, kAccountSpace, usernames);
   EXPECT_CALL(client, SendRequest(_, _))
       .WillOnce(Return(true));
   AccountSession session = CreateValidAccountSession();
   client.ReleaseAccount(session);
 }