Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/win/audio_manager_win.h

Index: media/audio/win/audio_manager_win.h
diff --git a/media/audio/win/audio_manager_win.h b/media/audio/win/audio_manager_win.h
index c315c812546523d44063304517fa81d8efc8993b..bce1772078c8c0abb60b78502511f88537e8589c 100644
--- a/media/audio/win/audio_manager_win.h
+++ b/media/audio/win/audio_manager_win.h
@@ -24,8 +24,10 @@ class MEDIA_EXPORT AudioManagerWin : public AudioManagerBase {
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
       AudioLogFactory* audio_log_factory);
+  ~AudioManagerWin() override;
 
   // Implementation of AudioManager.
+  void Shutdown() override;
   bool HasAudioOutputDevices() override;
   bool HasAudioInputDevices() override;
   base::string16 GetAudioInputDeviceModel() override;
@@ -57,8 +59,6 @@ class MEDIA_EXPORT AudioManagerWin : public AudioManagerBase {
   std::string GetDefaultOutputDeviceID() override;
 
  protected:
-  ~AudioManagerWin() override;
-
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;