https://gist.github.com/Ajnasz/fb7777184200504d4e47ad892583984a
To use the webRequest API for a given host, you must have the "webRequest" API permission. You must also have the host permission for both the host that initiated the request, and the target of the request. For example, if "foo.com" loads a resource from "bar.com", you must have permission for both those hosts. Note that this is stricter than Chrome, which only requires the host permission for the request's target.
Mivel gondolom minden weboldalon szeretnéd használni, ezért az <all_urls> kell a permissionök közé. https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns
--
HUP Firefox extension | Hupper hibajelentés