Add missing IWYU message_loop.h includes.

chrome/browser/safe_browsing/safe_browsing_service_browsertest.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.
 //
 // This test creates a safebrowsing service using test safebrowsing database
 // and a test protocol manager. It is used to test logics in safebrowsing
 // service.
 
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/path_service.h"
 #include "base/stl_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/thread_test_helper.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/bookmarks/startup_task_runner_service_factory.h"
@@ skipping 2460 matching lines @@
 }
 
 INSTANTIATE_TEST_CASE_P(
     MaybeSetMetadata,
     V4SafeBrowsingServiceMetadataTest,
     testing::Values(ThreatPatternType::NONE,
                     ThreatPatternType::MALWARE_LANDING,
                     ThreatPatternType::MALWARE_DISTRIBUTION));
 
 }  // namespace safe_browsing