Use ScopedTaskEnvironment instead of MessageLoop in chrome unit tests.

chrome/browser/local_discovery/local_domain_resolver_unittest.cc

 // Copyright 2014 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 <stdint.h>
 
 #include "base/location.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/local_discovery/service_discovery_client_impl.h"
 #include "net/dns/mdns_client_impl.h"
 #include "net/dns/mock_mdns_socket_factory.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using ::testing::_;
 
 namespace local_discovery {
@@ skipping 73 matching lines @@
     callback.Cancel();
   }
 
   MOCK_METHOD3(AddressCallbackInternal,
                void(bool resolved,
                     std::string address_ipv4,
                     std::string address_ipv6));
 
   net::MockMDnsSocketFactory socket_factory_;
   net::MDnsClientImpl mdns_client_;
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 };
 
 TEST_F(LocalDomainResolverTest, ResolveDomainA) {
   LocalDomainResolverImpl resolver(
       "myhello.local", net::ADDRESS_FAMILY_IPV4,
       base::Bind(&LocalDomainResolverTest::AddressCallback,
                  base::Unretained(this)), &mdns_client_);
 
   EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(2);  // Twice per query
 
@@ skipping 65 matching lines @@
   resolver.Start();
 
   EXPECT_CALL(*this, AddressCallbackInternal(false, "", ""));
 
   RunFor(base::TimeDelta::FromSeconds(4));
 }
 
 }  // namespace
 
 }  // namespace local_discovery