ChromeOS Version 63.0.3212.0 (Official Build) canary (64-bit)

What steps will reproduce the problem?
(1) Install an extension such as High Contrast. (I did this on my Windows machine and since I was signed into Chrome, it populated to all of my Chrome instances including on ChromeOS on my ChromeBook.) 
(2) Tab to the Omnibox then use Linear Navigation to put focus on the extension button. ChromeVox reads "High Contrast Button Extensions"
(3) Press enter to invoke the button.

What is the expected result? Menu of options collapses like it does in Chrome on Windows 

What happens instead? The focus rectangle jumps to the middle of whatever page I happen to be on. For example, I went to chrome://versions, performed the above steps, and focus jumped to the following text in the Command Line section: "default-wallpaper-large=/usr/share/chromeos-". It always jumps to this text.