bug#65710: xwidget-webkit cannot play video on Linux

[r09944008]

Quoting Eli Zaretskii <eliz@gnu.org>:

> > Date: Sun, 03 Sep 2023 01:28:02 +0800
> > From: r09944008@ntu.edu.tw
> >
> > As title. I visited a website using M-x xwidget-webkit-browse-url and
> > tried to play the video in it (ex: the video on https://www.gnu.org/),
> > but webkit hanging infinitely. I think this is a known issue as Po Lu
> > already flie a ticket to the webkit developers [1]. But currently the
> > issue is blocked by unable to reproduce the problem in the webkit
> > side. Hence I opened this one in the Emacs side for tracking and also
> > wish to raise the attention of Emacs graphics experts to help solving
> > the problems. Thanks.
>
> What is the Emacs problem we are supposed to investigate here, to help
> solving the problem?

IMHO we need to verify first if this is really a webkit's bug or it's  
actually Emacs own problems. The simplest way is to write some toy  
program to reproduce the issue without involving Emacs.

From the bug description, I saw Po mentioned that he "can't get video  
to play in a WebKitWebView attached to a GtkOffscreenWindow", it would  
be better to elaborate how the buggy code is written and see if we can  
extract those part into independent sample program and send it to the  
webkit team.

Thanks.