(non-null Array of number or undefined)
The track Ids that should be active.
(string or undefined)
Language for the tracks that should be active. The language field will take precedence over activeTrackIds if both are specified.
(non-null cast.receiver.media.TextTrackStyle or undefined)
The text track style.
(non-null Array of non-null cast.receiver.media.Track or undefined)
The tracks information.