Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/android/audio_manager_android.h

Index: media/audio/android/audio_manager_android.h
diff --git a/media/audio/android/audio_manager_android.h b/media/audio/android/audio_manager_android.h
index 2f3f2507f4e6eded405d17f1627b49c5fa5edc1d..c16f5b4f89c94ff7da501a31773f508d74661b2c 100644
--- a/media/audio/android/audio_manager_android.h
+++ b/media/audio/android/audio_manager_android.h
@@ -24,10 +24,12 @@ class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
       AudioLogFactory* audio_log_factory);
+  ~AudioManagerAndroid() override;
 
   void InitializeIfNeeded();
 
   // Implementation of AudioManager.
+  void Shutdown() override;
   bool HasAudioOutputDevices() override;
   bool HasAudioInputDevices() override;
   void GetAudioInputDeviceNames(AudioDeviceNames* device_names) override;
@@ -76,8 +78,6 @@ class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
   bool HasOutputVolumeOverride(double* out_volume) const;
 
  protected:
-  ~AudioManagerAndroid() override;
-
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;