chromium-browser been released 10/07/2016 - works in TX1!

Info:
https://launchpad.net/ubuntu/xenial/arm64/chromium-browser

Install:
http://launchpadlibrarian.net/287505994/chromium-browser_53.0.2785.143-0ubuntu0.16.04.1.1254_arm64.deb

Using it now in my own account, no longer log in as ubuntu…

Cheers,
Marc

Cheers!