Add missing IWYU message_loop.h includes.

base/threading/thread_perftest.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 <stddef.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/perf/perf_test.h"
@@ skipping 289 matching lines @@
 typedef EventPerfTest<PthreadEvent> PthreadEventPerfTest;
 TEST_F(PthreadEventPerfTest, EventPingPong) {
   RunPingPongTest("4_PthreadCondVar_Threads", 4);
 }
 
 #endif
 
 }  // namespace
 
 }  // namespace base