I'll give you the list of permissions I request (I don't know how firefox named them when displaying the notification to you):

1. contextMenus: to create context menu options (report, toggle...)
2. tabs: to gain access to tabs and to be able to add additional code to webpages (to hide warnings)
3. storage: to maintain whitelist
4. http://*/*: special permission to have access to any domain
5. https://*/*. the same, but for https
6. notifications: to be able to nofity users about updates
7. webRequest: to be able to see the request send by browser and check if it needs to be blocked (some javascript files which render cookie warnings)
8. webRequestBlocking: to block stuff from being loaded
9. webNavigation: to be able to apply filters when the page content is ready

I hope that helped.