Fullscreen-popup should be aligned with "fullscreen" Permission-Policy

[tungnh28]

Although "fullscreen" was removed from browser permission content setting, however, it is possible to not allow new window open in fullscreen by Permission Policy, such as header Permission-Policy: fullscreen=(). It would be an annoyance issue.

I only see the feature is gated behind "window-placement", but not "fullscreen" permission, should we provide an additional cases , giving a notice and escaping fullscreen mode?

[bradtriebwasser]

Some other things to consider.

• Should the permission policy be checked on the opener, or the opened window, or (probably) both. This should be documented in the explainer.
• Should the JS call be blocked (exception, console warning) if the opener, or opened page are blocked via permission policy?
• Is the permission policy headers available at the time the new window becomes fullscreen?
• Should both policies be considered? Should "fullscreen" blocked take precedence over window-management allow?

[tungnh28]

FYI, we are seeing enterprise policy would have the same effect as permission policy, to block the fullscreen.