Add missing IWYU message_loop.h includes.

media/renderers/audio_renderer_impl_unittest.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.
 
 #include "media/renderers/audio_renderer_impl.h"
 
 #include <memory>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/format_macros.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/stringprintf.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "media/base/audio_buffer_converter.h"
 #include "media/base/fake_audio_renderer_sink.h"
 #include "media/base/gmock_callback_support.h"
 #include "media/base/media_util.h"
 #include "media/base/mock_filters.h"
 #include "media/base/test_helpers.h"
@@ skipping 1067 matching lines @@
   // Advance far enough that we shouldn't be clamped to current time (tested
   // already above).
   tick_clock_->Advance(kOneSecond);
   EXPECT_EQ(
       current_time + timestamp_helper.GetFrameDuration(frames_to_consume.value),
       CurrentMediaWallClockTime(&is_time_moving));
   EXPECT_TRUE(is_time_moving);
 }
 
 }  // namespace media