Convert //media/audio from scoped_ptr to std::unique_ptr

chromecast/media/audio/cast_audio_manager_factory.h

Index: chromecast/media/audio/cast_audio_manager_factory.h
diff --git a/chromecast/media/audio/cast_audio_manager_factory.h b/chromecast/media/audio/cast_audio_manager_factory.h
index d80cc840853d290284b08fe7a2df6df8426e2d1b..26d7013b7025bedcd4bfe2c17e8ec5ce545f7160 100644
--- a/chromecast/media/audio/cast_audio_manager_factory.h
+++ b/chromecast/media/audio/cast_audio_manager_factory.h
@@ -20,7 +20,7 @@ class CastAudioManagerFactory : public ::media::AudioManagerFactory {
   ~CastAudioManagerFactory() override;
 
   // ::media::AudioManagerFactory overrides.
-  scoped_ptr<::media::AudioManager, ::media::AudioManagerDeleter>
+  std::unique_ptr<::media::AudioManager, ::media::AudioManagerDeleter>
   CreateInstance(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
                  scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
                  ::media::AudioLogFactory* audio_log_factory) override;