Web compat issue with permissions.query() in per-camera/mic permission models

[jan-ivar]

Permissions integration says: "If the descriptor does not have a deviceId, its semantic is that it queries for access to all devices of that class." — Since no-one's implemented deviceId, this is the norm for sites today:

const perm = await navigator.permissions.query({name: "camera"});
if (perm.state == "prompt") {
  nagTheUserAboutEnablingPermission();
}

But this site is trying to ask "can I call getUserMedia unprompted?", not "do I categorically have access to ALL cameras?"

Even after the site has a camera, Firefox cannot answer yes here, because it grants per-device permissions by default, not to ALL.

It would be more web compatible to say: "If the descriptor does not have a deviceId, its semantic is that it queries for access to the default device of that class."

Sites that truly wish to check the permission state of multiple cameras are able to do so.

[jan-ivar]

s/default device/any device/ based on offline feedback.

[dontcallmedom-bot]

This issue was discussed in WebRTC Feb 2023 Meeting – (Issue #927 🎞︎)