Add missing IWYU message_loop.h includes.

media/gpu/avda_codec_allocator.h

 // 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.
 
 #ifndef MEDIA_GPU_AVDA_CODEC_ALLOCATOR_H_
 #define MEDIA_GPU_AVDA_CODEC_ALLOCATOR_H_
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "base/android/build_info.h"
 #include "base/bind.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
 #include "base/optional.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/sys_info.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/tick_clock.h"
 #include "base/trace_event/trace_event.h"
 #include "media/base/android/android_overlay.h"
 #include "media/base/android/media_codec_bridge_impl.h"
 #include "media/base/android/media_drm_bridge_cdm_context.h"
@@ skipping 213 matching lines @@
 
   // For canceling pending StopThreadTask()s.
   base::WeakPtrFactory<AVDACodecAllocator> weak_this_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AVDACodecAllocator);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_GPU_AVDA_CODEC_ALLOCATOR_H_