--- a/dom/media/mediasource/MediaSourceDemuxer.cpp
+++ b/dom/media/mediasource/MediaSourceDemuxer.cpp
@@ -257,17 +257,17 @@ MediaSourceDemuxer::GetMozDebugReaderDat
   nsAutoCString result;
   result += nsPrintfCString("Dumping Data for Demuxer: %p\n", this);
   if (mAudioTrack) {
     result += nsPrintfCString(
       "\tDumping Audio Track Buffer(%s): mLastAudioTime=%f\n"
       "\t\tAudio Track Buffer Details: NumSamples=%zu"
       " Size=%u Evictable=%u "
       "NextGetSampleIndex=%u NextInsertionIndex=%d\n",
-      mAudioTrack->mAudioTracks.mInfo->mMimeType.get(),
+      mAudioTrack->mType.Type().AsString().get(),
       mAudioTrack->mAudioTracks.mNextSampleTime.ToSeconds(),
       mAudioTrack->mAudioTracks.mBuffers[0].Length(),
       mAudioTrack->mAudioTracks.mSizeBuffer,
       mAudioTrack->Evictable(TrackInfo::kAudioTrack),
       mAudioTrack->mAudioTracks.mNextGetSampleIndex.valueOr(-1),
       mAudioTrack->mAudioTracks.mNextInsertionIndex.valueOr(-1));
 
     result += nsPrintfCString(
@@ -275,17 +275,17 @@ MediaSourceDemuxer::GetMozDebugReaderDat
       DumpTimeRanges(mAudioTrack->SafeBuffered(TrackInfo::kAudioTrack)).get());
   }
   if (mVideoTrack) {
     result += nsPrintfCString(
       "\tDumping Video Track Buffer(%s): mLastVideoTime=%f\n"
       "\t\tVideo Track Buffer Details: NumSamples=%zu"
       " Size=%u Evictable=%u "
       "NextGetSampleIndex=%u NextInsertionIndex=%d\n",
-      mVideoTrack->mVideoTracks.mInfo->mMimeType.get(),
+      mVideoTrack->mType.Type().AsString().get(),
       mVideoTrack->mVideoTracks.mNextSampleTime.ToSeconds(),
       mVideoTrack->mVideoTracks.mBuffers[0].Length(),
       mVideoTrack->mVideoTracks.mSizeBuffer,
       mVideoTrack->Evictable(TrackInfo::kVideoTrack),
       mVideoTrack->mVideoTracks.mNextGetSampleIndex.valueOr(-1),
       mVideoTrack->mVideoTracks.mNextInsertionIndex.valueOr(-1));
 
     result += nsPrintfCString(