That's awesome! At Mozilla we've been daydreaming about incorporating something like that into the product. Especially with the proliferation of both in-browser content policies (CSP, Mixed Content blocking, etc.) and out-of-browser content policies (addons like Privacy Badger, ABP, Ghostery, etc.) it's almost impossible to understand the root cause of what's breaking a page, especially if you're not a technical user.
> but also making it work efficiently (wrote custom ABP engine from scratch which doesn't suffer the real one's abuse of memory/CPU)
For the Firefox version of Privacy Badger, we also eschewed the ABP engine in favor of something we wrote ourselves. Don't get me wrong, ABP is a great tool and we learned a lot from its code - but we wanted something as lean and performant as possible. I'd be interested to see the approach you took!
> only one extension is allowed to modify the HTTP headers
> it will break any previously installed extension
That sounds like a shortcoming in Chrome's Extension API. Firefox is somewhat better in that we do not restrict addons based on the behavior of other addons, so multiple addons are allowed to modify a request's headers. Unfortunately, the order in which the request is passed from handler to handler is not guaranteed, so in practice this may not end up being so useful.
We're trying to improve this situation by rewriting the Gecko Content Policy API [0], but that's a large project with no clear deadline.
[0] https://groups.google.com/forum/#!msg/mozilla.dev.platform/v...
Generally I think your addon and Privacy Badger are targeted at different audiences and have different use cases. It is too bad they are incompatible with each other - I, for one, would like to have both installed. Perhaps we can resolve this by talking to the Chrome devs about their Extension API?
- One of the Privacy Badger devs