The IOTization of any available media output seems to be the goal of the Chrome team: Chromecast, Chrome Audio, Chromebit. I like it.
Haven't had the time to check it really out, but seams to be 'iBeacons'.
That said, I believe Physical Web does use the Eddystone-URL mode.
Spec: https://github.com/google/eddystone/blob/master/protocol-spe...
Definitely check out the video on that page (it's only 5 minutes long). Also, Scott Jenson was interviewed on The Dirt podcast: http://www.freshtilledsoil.com/designing-for-the-future-pt-4...
edit:// Wikipedia article seem to state that is was more Android than Chrome OS https://en.wikipedia.org/wiki/Chromecast
However, a group managed to root it and figured out it was "more Android than ChromeOS", derived from Google TV of all things: https://blog.exploitee.rs/2013/chromecast-exploiting-the-new...