It is used for Crostini. Specifically, ChromeOS uses corssvm to run a virtual machine in which it runs LXD and then creates containers inside of that VM through it.

Google has sent the occasional bugfix, usually for pretty complex issues (hard to hit race and the like) but weren't involved in project maintenance or even very actively talking to us. We'd usually bump into the Crostini folks at conferences once or twice a year and just talk over dinner.