Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/fake_audio_manager.h

Index: media/audio/fake_audio_manager.h
diff --git a/media/audio/fake_audio_manager.h b/media/audio/fake_audio_manager.h
index 022c664c106d35aaee34563bf0a5559fea11e0a7..cc52022816f10107e9e4283fb8823bd2f7076059 100644
--- a/media/audio/fake_audio_manager.h
+++ b/media/audio/fake_audio_manager.h
@@ -20,6 +20,7 @@ class MEDIA_EXPORT FakeAudioManager : public AudioManagerBase {
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
       AudioLogFactory* audio_log_factory);
+  ~FakeAudioManager() override;
 
   // Implementation of AudioManager.
   bool HasAudioOutputDevices() override;
@@ -46,8 +47,6 @@ class MEDIA_EXPORT FakeAudioManager : public AudioManagerBase {
       const std::string& device_id) override;
 
  protected:
-  ~FakeAudioManager() override;
-
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;