Google Chrome 64.0.3250.0 (Official Build) canary (64-bit) (cohort: 64-Bit)
Windows 10 Enterprise Version 1607 Build 14393.1770
NVDA 2017.3
JAWS 2018.1710.42 private preview release
ZoomText Private Beta -  11.7.11.410

I expected the space bar to open the menu item in focus but it does not, enter key is required. This is just meant to check that this UI is correct. 

Steps to repro:
# Open AT software and then Chrome
# Navigate to Customize and Control Google Chrome menu
# Press space to collapse it
# Use arrow keys to put focus on any item
# Press space

Expected: space bar invokes the item like it would a button, etc.
Actual: space does nothing