Google Chrome	65.0.3319.0 (Official Build) canary (64-bit) (cohort: Clang-64)
Windows 10 Enterprise Version 1607 Build 14393.2007
NVDA 2017.4
JAWS 18.0.4534

Steps to repro: 

# Start any screen reader 
# Go to https://permission.site/
# Invoke the button that says Popup (delayed 2 seconds)
# See the popup blocker box on the right side of the Omnibox 
Expected: screen reader announces that this box exists 
Actual: no way to discover beyond using F6 to go to the Omnibox then tabbing to the icon that appears. 

This was also shown to reproduce on Mac with VoiceOver. 
This is related to CRBug.com/781578 (internal only bug)