Currently it's just a Chrome extension. The Chrome windows API is pretty decent. I think this "window manager" will have plenty of limitations, but I also think it might just be good enough. In parallel I'm also poking at ash a little bit, but I doubt I'd be able to take on such a large project and actually succeed.

This extension is a window manager that mimics Amethyst for OSX: https://github.com/brockgr/chrometile

It can give an idea of what's possible with the chrome.windows API.