I'm not yet convinced that Ryu (Pixel C) is just an Android tablet.
So despite being all over the chromium OS reviews list, Ryu was announced to the world as an all-Google, all-Android
tablet. This can make sense if either the Chromium team are also Google's designated consumer hardware team, or if Ryu was, at one stage, meant to at least dual-boot Chrome OS.
But if you go to the chromium issues page and search 'ryu' every single relevant entry appears under OS:Chrome, and some of these even post-date Ryu's announcement as running Android.
This bug seems particularly odd, given they're additionally, explicitly framing it as a Chromebook issue and then Ryu's name is nonchalantly rattled off: https://code.google.com/p/chromium/issues/detail?id=540817&q=ryu&sort=-modified&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Cr%20Status%20Owner%20Summary%20OS%20Modified
It's been mentioned by some of the media that the Pixel C could be Google's hardware for demoing this rumoured third OS, and what I'm seeing certainly leads credence to something
out of the usual being the case.