UserAgent: Mozilla/5.0 (X11; CrOS x86_64 10575.22.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.26 Safari/537.36
Platform: 10575.22.0 (Official Build) beta-channel swanky

Steps to reproduce the problem:
1. Go to chrome:flags and enable #enable-system-tray-unified
2. Apply changes (restart)
3. Get update (changing channels should make this process faster)
4. Open tray when update is ready to be installed

What is the expected behavior?
The update button does not appear.

What went wrong?
Upon trying to update my system which has not been used over the past few weeks, I found that the update button which has appeared before enabling #enable-system-tray-unified does not appear. 

This may be confusing if this flag is implemented as the norm on all devices and may need a revision of the HC document:

https://support.google.com/chromebook/answer/177889

Another problem to note is that the "old" version of the tray appears when clicking on the accessibility button and then the back button.

Did this work before? N/A 

Chrome version: 67.0.3396.26  Channel: n/a
OS Version: 10575.22.0
Flash Version: 29.0.0.168 

Submitted feedback via Shift + Alt + I with the last line as "#enable-system-tray-unified"