Tested only VSE portion now
It seems that for movie clip this change doesn't move progress, but also shows it in the status bar, making it so progress is displayed in both clip editor's header and status bar. I don't think this is a great redundancy.
Also think if the progress is to be always displayed in the status bar, do we still need an owner parameter to WM_jobs_get() ?
There are unused variables warnings induced by this change:
tracking_ops_solve.c:194:12: warning: unused variable ‘sa’ [-Wunused-variable]
tracking_ops_track.c:291:12: warning: unused variable ‘sa’ [-Wunused-variable]
Technically no, but some editors may rely on owner when they build up queue(context may be part of jobs customdata, not queue element itself)?
I can go through all callees to check, there are not so many.