Google Chrome 66.0.3353.0 (Official Build) canary (64-bit) (cohort: Clang-64)
Related documentation on the G Suite side indicates that alt + letter works on Chrome/Chrome OS but other browsers require alt + shift + letter:  https://support.google.com/docs/answer/181110

Steps to repro:
# Launch Chrome and about:blank (or another page that doesn't capture keystrokes)
# Press alt + f
Expected/Actual: Customize and Control Chrome menu opens with focus on menu button
# Press esc or otherwise take focus off menu
# Launch Chrome and any doc at docs.google.com
# Bring focus into the doc itself by clicking/typing etc.
# Press Alt + f 
Expected/Actual: Docs File menu opens
# With Focus still on the Doc, press Alt + f again
Expected: the focus stays in the Doc menu
Actual: Chrome menu opens (Customize and Control Chrome)
# Bring focus to another Chrome tab by pressing ctrl + t or using any other keystrokes to navigate to another tab (ctrl + number or ctrl + page up/down, etc.)
# Bring focus back onto the tab containing the Doc. Do not put focus into the Doc itself. 
# Press Alt + F
Expected: Docs still captures the keystroke, Docs menu opens
Actual: Chrome menu opens 

Another complication of this bug is that pressing either alt + f or alt + e twice in a row will repro this bug behavior of different menus opening. An example case where this would be extra confusing to a user would be having focus in the Doc, pressing alt + f for file, changing your mind and wanting to opening alt + e for edit and having the Chrome menu open instead.