This bug is in the Select-to-speak extension, not Settings (id: klbcgckkldhdhonijdbnhhaiedfkllef).

->a11y for triage

Looks like tab does select the button, but the style isn't changing when it is focused. We are using a checkbox with a custom icon here rather than a cr-toggle (which has a nice ripple built-in).

Repro: Tab three times to get to the button. Hit "space" , and the toggle is switched on or off.

Two possible solutions:
1. Can we use cr-toggle here and in ChromeVox too?
2. Get some images with the ripple and just set those for checked/unchecked focus

1. Can we use cr-toggle here and in ChromeVox too?

Not with the current architecture, since S2S and ChromeVox are extensions and don't have access to the the rest of the WebUI architecture.

It'd be possible, and interesting, to make use of classes like cr-toggle, but it'd be a lot of work to set up at first.

2. Get some images with the ripple and just set those for checked/unchecked focus

This seems like the easiest.

Perhaps the best solution would be to make S2S options just part of the main Chrome options page. It really ought to act more like a built-in feature and not like a separate extension. It could be in a sub-page, or the options could just slide out when you enable S2S. We should go through UI review for that.

That's a bit more work, but certainly much less work than making it possible for extensions to use cr-toggle.

We'd probably need UX approval to move the S2S options into the Chrome options page. 
@lpalmaro, do you think UX would consider adding all these STS options, visually, into the chrome::settings/manageAccessibility page?

In addition, the same thing is seen in Chromevox, which may be too many options to port into the Chrome options page.

Issue 883239 has been merged into this issue.