It does use X11, but ChromeOS uses its own WM (chromewm). If you check out the sources for ChromiumOS, you can see what all it uses, although there are parts th

It does use X11, but ChromeOS uses its own WM (chromewm). If you check out the sources for ChromiumOS, you can see what all it uses, although there are parts that Google add on top. There are ways to run native apps on it, but they are definitely tucked away for normal users/uses.