A previous analysis (https://docs.google.com/document/d/1WaHH75xD4mx96KrJN1GT_DMIZYc93BW1l5JgkQuxHnU/edit?ts=5bc910fd#bookmark=id.9uxrqpx65k6r) showed that some extensions add a DNT request header on every request. This is potentially expensive. We already have a "Send a "Do Not Track" request with your browsing traffic" setting. Find out if it makes sense to expose this through an extension API.