Are you saying that, like if music app is using MediaRemoteControls, at the time the player needs to notify the play status or metadata, the player should create its own custom event to trigger MediaRemoteControls to update the information for itself? if so, I think there will be some external code that the music player, or even the video player(in the future) which might include the remote_controls.js needs to implement, I just afraid if we have design like this, the players still needs to write a bunch of code to complete the features.