Convert MediaLog from being ref counted to owned by WebMediaPlayer.

content/renderer/media/webmediaplayer_ms.h

Index: content/renderer/media/webmediaplayer_ms.h
diff --git a/content/renderer/media/webmediaplayer_ms.h b/content/renderer/media/webmediaplayer_ms.h
index d44d94ede9e8d03a4b1cd15e33d606eac288c0d9..debec32db9f73eab46b3ea743f6e13162ebb3179 100644
--- a/content/renderer/media/webmediaplayer_ms.h
+++ b/content/renderer/media/webmediaplayer_ms.h
@@ -73,7 +73,7 @@ class CONTENT_EXPORT WebMediaPlayerMS
       blink::WebFrame* frame,
       blink::WebMediaPlayerClient* client,
       media::WebMediaPlayerDelegate* delegate,
-      media::MediaLog* media_log,
+      std::unique_ptr<media::MediaLog> media_log,
       std::unique_ptr<MediaStreamRendererFactory> factory,
       scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_,
       scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner,
@@ -233,7 +233,7 @@ class CONTENT_EXPORT WebMediaPlayerMS
   bool paused_;
   media::VideoRotation video_rotation_;
 
-  scoped_refptr<media::MediaLog> media_log_;
+  std::unique_ptr<media::MediaLog> media_log_;
 
   std::unique_ptr<MediaStreamRendererFactory> renderer_factory_;