Copied from issue 869608

69.0.3497.21 (Official Build) dev (64-bit)

It is weird since ChromeVox users wouldn't use the mouse at all. Select to Speak users would use the mouse often, though. 

Steps used to repro: 
# Enable ChromeVox with ctrl + alt z or Select To Speak using the Settings > Accessibility features (depending on test, see results below). Note that you shouldn't run both tools together, that's not supported. 
# Lock screen (you need to first use the passthrough command of search + shift + esc to be able to use search + l to lock the screen)
# unlock screen
# wait a few seconds
# open help dialog/app with Ctrl-Alt-/
# wait 10 sec while searching with ChromeVox or using Select To Speak on items listed in the dialog 
# Close the dialog using the x button, not with ctrl + w

Repeat these steps several times with ChromeVox enabled: 
1: nothing unusual
2: ChromeVox freezes, pressing tab does nothing, stops speaking for several seconds, then recovers. No unusual behavior with the help dialog. 
3: Same as two, ChromeVox freezes for several seconds then recovers

Look at the ChromeVox screen reader logs using these steps:
# Turn on ChromeVox with ctrl + alt + z
# Navigate to chrome://inspect/#extensions
# Follow steps above to general freeze
During the freeze, this error is shown:
chromeVox2ChromeBackgroundScript.js:785 Missing role info for unknown
(anonymous) @ chromeVox2ChromeBackgroundScript.js:785
format_ @ chromeVox2ChromeBackgroundScript.js:758
node_ @ chromeVox2ChromeBackgroundScript.js:857
(anonymous) @ chromeVox2ChromeBackgroundScript.js:833
range_ @ chromeVox2ChromeBackgroundScript.js:837
render_ @ chromeVox2ChromeBackgroundScript.js:757
withLocation @ chromeVox2ChromeBackgroundScript.js:743
onScrollPositionChanged @ chromeVox2ChromeBackgroundScript.js:2099
(anonymous) @ chromeVox2ChromeBackgroundScript.js:1854
fireEventListeners_ @ extensions::automationNode:817
dispatchEventAtCapturing_ @ extensions::automationNode:778
dispatchEvent @ extensions::automationNode:745
onAccessibilityEvent @ extensions::automationNode:1371
(anonymous) @ extensions::automation:298

When trying to use Select to Speak over this dialog, STS failed to speak 2/5 times. However, there were no crashes for the dialog, nothing logged in the console during this time.

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James says:
In M69 we should be using the legacy (non-app) version of this dialog when STS is enabled, so I wonder if the STS issues are something else.

The freeze might be related to  issue 867654 , existing windows not reactivating when the shortcut viewer is closed.