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..a40e7159ef1eac1cec6228d9e3885ea763ae220b 100644
--- a/media/audio/fake_audio_manager.h
+++ b/media/audio/fake_audio_manager.h
@@ -16,10 +16,9 @@ namespace media {
 
 class MEDIA_EXPORT FakeAudioManager : public AudioManagerBase {
  public:
-  FakeAudioManager(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
-      AudioLogFactory* audio_log_factory);
+  FakeAudioManager(std::unique_ptr<AudioThread> audio_thread,
+                   AudioLogFactory* audio_log_factory);
+  ~FakeAudioManager() override;
 
   // Implementation of AudioManager.
   bool HasAudioOutputDevices() override;
@@ -46,8 +45,6 @@ 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;