Make screen sharing works on Chrome using getDisplayMedia()

[mjattiot]

Screen sharing has never been working on recent versions of Chrome (fixes element-hq/element-web#6181).

This PR intends to use the new API getDisplayMedia() to make it works on all recent browsers : https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getDisplayMedia

Signed-off-by: Maxime Jattiot mjattiot@opensense.fr

[jryans]

MDN support info is apparently outdated, as it seems Safari 13 on desktop is supported as well.

We should test in all 3 supported browsers as part of the review to be sure it does indeed work.

[turt2live]

The change itself looks fine, and testing it feels non-trivial on all three browsers. https://caniuse.com/#search=getDisplayMedia also says Safari is not supported.

@jryans where are you seeing that it is supported? If it is in fact supported and all the sources are wrong, I'd be inclined to merge this and test it live instead of trying to test it ourselves. This is a low-traffic part of the repo and this is a relatively atomic change to back out.

[mjattiot]

Well the function exists on Safari 13:

However I tried to make it works on a console without success, nothing happens when I click:

And it seems Riot on Safari doesn't currently support screensharing anyway ...

Still this feature is a must have for Chrome and supported by Firefox as well. So I campaign for a merge ! :)

[jryans]

Ah okay, my evidence for Safari was:

• A blog post about it seeming to work
• This detection page claiming it works when I checked in Safari

Anyway, as already mentioned, we don't support Safari for VoIP today, so there's no regression to worry about.