Convert MediaLog from being ref counted to owned by WebMediaPlayer.

media/formats/webm/webm_tracks_parser.h

Index: media/formats/webm/webm_tracks_parser.h
diff --git a/media/formats/webm/webm_tracks_parser.h b/media/formats/webm/webm_tracks_parser.h
index 8cef4fbac186a4dc0ee75afed4c847f1e7e559f0..1e8cb04b16617fee2c6bf6f87431d0abda12020a 100644
--- a/media/formats/webm/webm_tracks_parser.h
+++ b/media/formats/webm/webm_tracks_parser.h
@@ -31,8 +31,7 @@ namespace media {
 // Parser for WebM Tracks element.
 class MEDIA_EXPORT WebMTracksParser : public WebMParserClient {
  public:
-  WebMTracksParser(const scoped_refptr<MediaLog>& media_log,
-                   bool ignore_text_tracks);
+  WebMTracksParser(MediaLog* media_log, bool ignore_text_tracks);
   ~WebMTracksParser() override;
 
   // Parses a WebM Tracks element in |buf|.
@@ -126,7 +125,7 @@ class MEDIA_EXPORT WebMTracksParser : public WebMParserClient {
   std::set<int64_t> ignored_tracks_;
   std::string audio_encryption_key_id_;
   std::string video_encryption_key_id_;
-  scoped_refptr<MediaLog> media_log_;
+  MediaLog* media_log_;
 
   WebMAudioClient audio_client_;
   AudioDecoderConfig audio_decoder_config_;