Add missing IWYU message_loop.h includes.

components/tracing/test/trace_event_perftest.cc

 // Copyright 2016 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 "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted_memory.h"
+#include "base/message_loop/message_loop.h"
 #include "base/pending_task.h"
 #include "base/run_loop.h"
 #include "base/threading/thread.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "perf_test_helpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace tracing {
 namespace {
@@ skipping 164 matching lines @@
   EndTraceAndFlush();
 }
 
 TEST_F(TraceEventPerfTest, Submit_10000_TRACE_EVENT0_with_tracing_disabled) {
   ScopedStopwatch stopwatch("events");
   SubmitTraceEvents(10000);
 }
 
 }  // namespace
 }  // namespace tracing