In add-on sdk there is the page-worker, in the webextensions guidelines there is wrote: Use the background page, or load remote iframes into the background page. In background html page there are 2 frame, in the background script I will assign the src value to www.google.com www.example.com, but when I try to get iframe contents I got permission denied. It is possibile to do the same thinks of page-worker? how? (it can be useful to add a sample in the webextensions guide)