This will ship in Chrome OS Milestone 67. It's also available in M65 using Google #enable-experimental-accessibility-features. 

The following are needed documentation updates: 
Search key silences speech per https://bugs.chromium.org/p/chromium/issues/detail?id=819925

Behavior around Google Drive products per https://bugs.chromium.org/p/chromium/issues/detail?id=812683

* STS destroys the clipboard in Google Docs, Drawings, Slides and Sheets when using Search + S. This is expected.
* Word highlighting doesn't work in Google Docs, Drawings, Slides and Sheets when using Search + S. This is expected.
* The clipboard is not destroyed in Google Forms or Sites, this is correct. Clipboard is only destroyed in Docs, Drawings, Slides and Sheets.