Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/audio_thread.h

+// Copyright 2017 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_THREAD_H_
+#define MEDIA_AUDIO_AUDIO_THREAD_H_
+
+#include "media/base/media_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace media {
+
+// This class encapulates the logic for the thread and task runners that the
+// AudioManager and related classes run on.
+class MEDIA_EXPORT AudioThread {
+ public:
+  virtual ~AudioThread() {}
+
+  // Synchronously stops all underlying threads.
+  // Both - GetTaskRunner and GetWorkerTaskRunner - will return null after this

[o1ka, 2017/04/28 13:24:20]

Should AudioManager check for null?

[alokp, 2017/05/09 19:06:15]

Removed comment. Now we continue to return a task runner after stop.

+  // function is called.
+  virtual void Stop() = 0;
+
+  // Returns the task runner used for audio IO.
+  virtual base::SingleThreadTaskRunner* GetTaskRunner() = 0;
+
+  // Heavyweight tasks should use GetWorkerTaskRunner() instead of
+  // GetTaskRunner(). On most platforms they are the same, but some share the
+  // UI loop with the audio IO loop.
+  virtual base::SingleThreadTaskRunner* GetWorkerTaskRunner() = 0;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_AUDIO_THREAD_H_