``` struct AudioTrackInformation { RefPtr<MediaDescription> description; RefPtr<AudioTrackPrivate> track; }; Vector<AudioTrackInformation> audioTracks; struct VideoTrackInformation { RefPtr<MediaDescription> description; RefPtr<VideoTrackPrivate> track; }; Vector<VideoTrackInformation> videoTracks; struct TextTrackInformation { RefPtr<MediaDescription> description; RefPtr<InbandTextTrackPrivate> track; }; ``` They can never be null, I believe RefPtr was used as Ref<t> didn't exist at the time
<rdar://problem/107366003>