Convert MediaLog from being ref counted to owned by WebMediaPlayer.

media/blink/webmediasource_impl.cc

Index: media/blink/webmediasource_impl.cc
diff --git a/media/blink/webmediasource_impl.cc b/media/blink/webmediasource_impl.cc
index 4c54f22403eebf58f984a0ef5ae2b7806e34b5e6..812b9cc1eb4749fbdb747ce22e07b98e0a63e13c 100644
--- a/media/blink/webmediasource_impl.cc
+++ b/media/blink/webmediasource_impl.cc
@@ -24,9 +24,8 @@ STATIC_ASSERT_MATCHING_STATUS_ENUM(kAddStatusNotSupported, kNotSupported);
 STATIC_ASSERT_MATCHING_STATUS_ENUM(kAddStatusReachedIdLimit, kReachedIdLimit);
 #undef STATIC_ASSERT_MATCHING_STATUS_ENUM
 
-WebMediaSourceImpl::WebMediaSourceImpl(ChunkDemuxer* demuxer,
-                                       const scoped_refptr<MediaLog>& media_log)
-    : demuxer_(demuxer), media_log_(media_log) {
+WebMediaSourceImpl::WebMediaSourceImpl(ChunkDemuxer* demuxer)
+    : demuxer_(demuxer) {
   DCHECK(demuxer_);
 }