Automated IWYU fix for TaskRunner includes.

media/audio/audio_manager_base.h

 // 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.
 
 #ifndef MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 
 #include <memory>
 #include <string>
 #include <unordered_set>
 #include <utility>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
+#include "base/single_thread_task_runner.h"
 #include "base/threading/thread.h"
 #include "build/build_config.h"
 #include "media/audio/audio_debug_recording_manager.h"
 #include "media/audio/audio_device_name.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_output_dispatcher.h"
 
 #if defined(OS_WIN)
 #include "base/win/scoped_com_initializer.h"
 #endif
@@ skipping 172 matching lines @@
 
   // Debug recording manager.
   std::unique_ptr<AudioDebugRecordingManager> debug_recording_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerBase);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_