Pass task runners to AudioManager constructor.

media/audio/audio_manager.h

Index: media/audio/audio_manager.h
diff --git a/media/audio/audio_manager.h b/media/audio/audio_manager.h
index d3eea4a6b9cdcf5b944e076dc12e983a82109b05..c878d003c000a4f9b82e2140adbb0b6f6a0ce32a 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -22,9 +22,16 @@ class SingleThreadTaskRunner;
 namespace media {
 
 class AudioInputStream;
+class AudioManager;
 class AudioManagerFactory;
 class AudioOutputStream;
 
+class AudioManagerDeleter {
+ public:
+  void operator()(const AudioManager* instance) const;
+};
+using ScopedAudioManagerPtr = scoped_ptr<AudioManager, AudioManagerDeleter>;
+
 // Manages all audio resources.  Provides some convenience functions that avoid
 // the need to provide iterators over the existing streams.
 //
@@ -35,7 +42,6 @@ class AudioOutputStream;
 class MEDIA_EXPORT AudioManager {
  public:
   virtual ~AudioManager();
-
   // This provides an alternative to the statically linked factory method used
   // to create AudioManager. This is useful for dynamically-linked third
   // party clients seeking to provide a platform-specific implementation of
@@ -46,20 +52,27 @@ class MEDIA_EXPORT AudioManager {
   // which must not be NULL.
   static void SetFactory(AudioManagerFactory* factory);
 
-  // Construct the audio manager; only one instance is allowed.  The manager
-  // will forward CreateAudioLog() calls to the provided AudioLogFactory; as
-  // such |audio_log_factory| must outlive the AudioManager.
-  static AudioManager* Create(AudioLogFactory* audio_log_factory);
-
-  // Similar to Create() except also schedules a monitor on the given task
-  // runner to ensure the audio thread is not stuck for more than 60 seconds; if
-  // a hang is detected, the process will be crashed.  See EnableHangMonitor().
-  static AudioManager* CreateWithHangTimer(
-      AudioLogFactory* audio_log_factory,
-      const scoped_refptr<base::SingleThreadTaskRunner>& monitor_task_runner);
-
-  // Similar to Create() except uses a FakeAudioLogFactory for testing.
-  static AudioManager* CreateForTesting();
+  // Construct the audio manager; only one instance is allowed.

[tommi (sloooow) - chröme, 2016/03/19 02:32:41]

since it has come up a few times in the past and been the source of confusion,
can you call out explicitly which one of the below threads will be the UI thread
on Mac?

[alokp, 2016/03/22 21:47:07]

Done.

+  // The returned instance must be deleted on AudioManager::GetTaskRunnner().
+  //
+  // The manager will forward CreateAudioLog() calls to the provided
+  // AudioLogFactory; as such |audio_log_factory| must outlive the AudioManager.
+  //
+  // The manager will use |task_runner| for audio IO. If the given |task_runner|
+  // is NULL, the implementation will choose a default task runner, which can
+  // be obtained by calling GetTaskRunner().
+  //
+  // The manager will use |worker_task_runner| for heavyweight tasks.
+  // The |worker_task_runner| may be the same as |task_runner| or NULL, in
+  // which case the implementation will choose a default one.
+  //
+  // If |monitor_task_runner| is not NULL, a monitor will be scheduled on
+  // |monitor_task_runner| to monitor |task_runner|. See EnableHangMonitor().
+  static ScopedAudioManagerPtr Create(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner,

[tommi (sloooow) - chröme, 2016/03/19 02:32:41]

nit: passing by value implies that the caller might want to pass ownership. I'm
not sure that's true though since at least some of these task runners are held
elsewhere.

[alokp, 2016/03/22 21:47:07]

I agree. I plan to look into it in a later patch. Please see my response in BML.

+      scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> monitor_task_runner,
+      AudioLogFactory* audio_log_factory);
 
   // Enables non-crash dumps when audio thread hangs are detected.
   // TODO(dalecurtis): There are no callers to this function at present. A list
@@ -178,12 +191,18 @@ class MEDIA_EXPORT AudioManager {
       const std::string& device_id) = 0;
 
   // Returns the task runner used for audio IO.
-  virtual scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() = 0;
+  // TODO(alokp): Rename to task_runner().
+  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() const {
+    return task_runner_;
+  }
 
   // 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 scoped_refptr<base::SingleThreadTaskRunner> GetWorkerTaskRunner() = 0;
+  // TODO(alokp): Rename to worker_task_runner().
+  scoped_refptr<base::SingleThreadTaskRunner> GetWorkerTaskRunner() const {
+    return worker_task_runner_;
+  }
 
   // Allows clients to listen for device state changes; e.g. preferred sample
   // rate or channel layout changes.  The typical response to receiving this
@@ -230,9 +249,12 @@ class MEDIA_EXPORT AudioManager {
       AudioLogFactory::AudioComponent component) = 0;
 
  protected:
-  AudioManager();
+  AudioManager(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+               scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner);
 
  private:
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner_;
   DISALLOW_COPY_AND_ASSIGN(AudioManager);
 };