Convert MediaLog from being ref counted to owned by WebMediaPlayer.

media/filters/ffmpeg_video_decoder.h

Index: media/filters/ffmpeg_video_decoder.h
diff --git a/media/filters/ffmpeg_video_decoder.h b/media/filters/ffmpeg_video_decoder.h
index 0c107f651cb97c4b97e6a2abe2767f7d3a30396d..7737e4b8c36c311e975fa6361e7ad765ae851071 100644
--- a/media/filters/ffmpeg_video_decoder.h
+++ b/media/filters/ffmpeg_video_decoder.h
@@ -29,7 +29,7 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
  public:
   static bool IsCodecSupported(VideoCodec codec);
 
-  explicit FFmpegVideoDecoder(scoped_refptr<MediaLog> media_log);
+  explicit FFmpegVideoDecoder(MediaLog* media_log);
   ~FFmpegVideoDecoder() override;
 
   // Allow decoding of individual NALU. Entire frames are required by default.
@@ -75,7 +75,7 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
   void ReleaseFFmpegResources();
 
   base::ThreadChecker thread_checker_;
-  scoped_refptr<MediaLog> media_log_;
+  MediaLog* media_log_;
 
   DecoderState state_;