Cleanup AudioDeviceThread to avoid accidental misuse.

content/browser/audio_device_thread.h

Index: content/browser/audio_device_thread.h
diff --git a/content/browser/audio_device_thread.h b/content/browser/audio_device_thread.h
index 1547686e1d6e6f1fcb415e212ccbc99cbee0143d..cd4b52c7c4220c36c41f03869208d2495c125c67 100644
--- a/content/browser/audio_device_thread.h
+++ b/content/browser/audio_device_thread.h
@@ -5,6 +5,7 @@
 #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"
 
@@ -16,18 +17,28 @@ namespace content {
 // 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);
 };