This no longer does anything, and it was marked as CONSTRUCT_ONLY
which means someone would really have to go out of their way to
be able to set this, which would only be done in very custom
scenarios, if ever, and those will likely target a specific
version of GStreamer then, so probably not much point keeping
it deprecated for a while before removing it.
Created a unit test for dashdemux. It relies on a fake SOUP HTTP src plugin
that will feed data to dashdemux. The test controls the data to be
generated and checks the correct data was received for each expected
stream.
https://bugzilla.gnome.org/show_bug.cgi?id=756322
