Interaction between browser and system permissions

[marcoscaceres]

At w3c/geolocation#107 (comment), @reillyeon suggested:

a note in the Permissions spec about how per-site and system-level permissions should stack would be helpful across this [Geolocation] and other permissions which face similar issues.

[reillyeon]

The specific question from that issue which should be decided at the Permissions API level is how per-site and system-level permissions interact when calling navigator.permissions.query(). In w3c/geolocation#107 @marcoscaceres clarified how the Geolocation API should behave when system-level permission is denied but it is still unspecified how the Permissions API should behave. The two options seem to be,

1. Be consistent between the API providing the powerful feature and the Permissions API and return "denied" when the system-level permission is denied regardless of the per-site state.
2. Only reflect the per-site state in the Permissions API. Explicitly support sites using this inconsistency as a way to detect a situation in which system-level permission has not been granted.

[marcoscaceres]

Related Gecko bug/discussion: https://bugzilla.mozilla.org/show_bug.cgi?id=1494172 (may help further inform the discussion)

[reillyeon]

Discussed at TPAC 2024. I will put up a PR with some text based on what the room seemed to agree with.

[npdoty]

If we stopped relying on query() (which I still think is often harmful), when a site actually tried to use a camera or geolocation permission and the browser allowed it but the OS didn't, that might be a time that the browser could remind the user of their inconsistent state and explain the problem 'you wanted to use your camera with this site, but the browser doesn't have permission to use the camera'.