Clean Exit from command line?

[kmand]

I'm on Ubuntu and occasionally my display freezes for issues not related to Chromium. In some cases I just have to kill the session or even reboot.  I can ssh in from another machine. I have a lot of browser tabs and windows,  and really want a clean Chromium shut down. I've tried sending various signals to Chromium but never seem to have found one that actually  does the clean exit I would get if I could use the Chromium menu.

What should I use?