[mediacapture-main] Should getUserMedia promise be resolved only on pages that have focus (#560)

youennf has just created a new issue for https://github.com/w3c/mediacapture-main:

== Should getUserMedia promise be resolved only on pages that have focus ==
Safari currently does not resolve/reject a getUserMedia promise until the view is visible.
This allows to start capture on a page that the user has access to.
Should this be mandated in the spec?
The same question might apply to enumerateDevices.

Please view or discuss this issue at https://github.com/w3c/mediacapture-main/issues/560 using your GitHub account