Pass task runners to AudioManager constructor.

media/audio/audio_thread.h

+// Copyright 2016 The Chromium Authors. All rights reserved.

[DaleCurtis, 2016/03/18 17:48:19]

What is this class getting us? It seems to be pretty much just a typedef.

[alokp, 2016/03/18 18:40:07]

It lazily creates the thread. See AudioThread::Get and the lazyinstance in cc
file.

Do see my comment in audio_manager.h and browser_main_loop.cc about how we can
avoid this class by creating a local thread in BML and adding
ContentBrowserClient::GetAudioTaskRunner.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_AUDIO_AUDIO_THREAD_H_
+#define MEDIA_AUDIO_AUDIO_THREAD_H_
+
+#include "base/macros.h"
+#include "base/threading/thread.h"
+
+namespace media {
+
+class AudioThread {
+ public:
+  AudioThread();
+  static base::Thread* Get();
+
+ private:
+  base::Thread thread_;
+  DISALLOW_COPY_AND_ASSIGN(AudioThread);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_AUDIO_THREAD_H_