UserAgent: Mozilla/5.0 (X11; Linux armv7l) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/62.0.3202.94 Chrome/62.0.3202.94 Safari/537.36

Steps to reproduce the problem:
1.$ chromium-browser --kiosk --incognito google.com &
2.$ sudo pkill chromium-browser*   (or ALT+F4)
3.$ sudo reboot  (or shutdown -r or GUI reboot button)

What is the expected behavior?
PC have to reboot but it will shutdown.

What went wrong?
It stuck on the reboot

Did this work before? N/A 

Chrome version: 62.0.3202.94  Channel: stable
OS Version: Ubuntu 16.04.3
Flash Version: 

in case without closing chromium all works well:

$ chromium-browser --kiosk --incognito google.com &
$ sudo reboot

All is OK

in case with closing and reopening chrome all works well:
$ chromium-browser --kiosk --incognito google.com &
$ sudo pkill chromium-browser*
$ chromium-browser --kiosk --incognito google.com &
$ sudo reboot

All is OK

(tested on two different PC with different hardware and OS releases)