Cleanup AudioDeviceThread to avoid accidental misuse.

content/browser/audio_device_thread.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 CONTENT_BROWSER_AUDIO_DEVICE_THREAD_H_
 #define CONTENT_BROWSER_AUDIO_DEVICE_THREAD_H_
 
+#include "base/memory/ref_counted.h"
 #include "base/threading/thread.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // This class encapulates the logic for the thread and task runners that the
 // AudioManager and related classes run on. audio_task_runner and
 // worker_task_runner should be called on the same thread as the
 // AudioDeviceThread was constructed on.
 class CONTENT_EXPORT AudioDeviceThread {
  public:
-  // Constructs and starts the thread.
+  // Constructs and starts a thread. On all platforms except for OSX, the

[Avi (use Gerrit), 2016/12/13 01:36:11]

"OSX" isn't really a thing any more. Say "the Mac" or "macOS".

[DaleCurtis, 2016/12/13 01:55:39]

Done.

+  // started thread becomes the audio task runner. However, on OSX, the task
+  // runner this object is constructed on will become the audio thread and the
+  // thread is only used for high complexity tasks which can't be run on the
+  // main thread (typically the UI thread).
   AudioDeviceThread();
+  ~AudioDeviceThread();
 
-  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner();
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner() const {
+    return task_runner_;
+  };
 
-  scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner() {
+  scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner() const {
     return thread_.task_runner();
   }
 
  private:
   base::Thread thread_;
 
+  // Task runner to run audio control calls on.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioDeviceThread);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_AUDIO_DEVICE_THREAD_H_