PS: If it's so important to reclaim the RAM if a music is not
being played, Frederik's idea of keeping the controls on
the menu regardless if the app is open and starting up the
app on demand could work.
If the player is not running, or if it is running but has no active track, the playback item should not be present by default. However, the API should provide a way for a player to register a Play action, so that the Play button can work even when the player is not running. If this has been done, the whole playback item should be present, but the Back and Forward buttons should be insensitive.