Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/pulse/audio_manager_pulse.h

Index: media/audio/pulse/audio_manager_pulse.h
diff --git a/media/audio/pulse/audio_manager_pulse.h b/media/audio/pulse/audio_manager_pulse.h
index 662c4614a8ce97effbb19885ae7b82e8db50e2dc..12a88f5fc1433e63c011810cea73c43375609136 100644
--- a/media/audio/pulse/audio_manager_pulse.h
+++ b/media/audio/pulse/audio_manager_pulse.h
@@ -17,10 +17,9 @@ namespace media {
 
 class MEDIA_EXPORT AudioManagerPulse : public AudioManagerBase {
  public:
-  AudioManagerPulse(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
-      AudioLogFactory* audio_log_factory);
+  AudioManagerPulse(std::unique_ptr<AudioThread> audio_thread,
+                    AudioLogFactory* audio_log_factory);
+  ~AudioManagerPulse() override;
 
   bool Init();
 
@@ -52,8 +51,7 @@ class MEDIA_EXPORT AudioManagerPulse : public AudioManagerBase {
       const LogCallback& log_callback) override;
 
  protected:
-  ~AudioManagerPulse() override;
-
+  void ShutdownOnAudioThread() override;
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;