The idea was that the Media Extractor could wrap the original source
given by BMediaTrack, but all operations on the data go through
MediaExtractor anyway.
We could probably move ownership of the BDataIO completely into
MediaExtractor instead.
Change-Id: I846b34b543fb983e60f6adf86cb17e835303267b
Reviewed-on: https://review.haiku-os.org/c/1587
Reviewed-by: Stephan Aßmus <superstippi@gmx.de>
727e49c611