Interface definition for a callback to be invoked when the media playback position is requested to be updated.
Called on the implementer to notify it that the playback head should be set at the given position.
Called on the implementer to notify it that the playback head should be set at the given
position. If the position can be changed from its current value, the implementor of
the interface must also update the playback position using
setPlaybackState(int, long, float) to reflect the actual new
position being used, regardless of whether it differs from the requested position.
Failure to do so would cause the system to not know the new actual playback position,
and user interface components would fail to show the user where playback resumed after
the position was updated.