The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3019ca46a6050d6b64c198a6eadaca9ca83e3436

commit 3019ca46a6050d6b64c198a6eadaca9ca83e3436
Author: Zach Helfinstein <zhelfins@chromium.org>
Date: Wed Aug 22 22:54:21 2018

Allow SwitchAccess to traverse VirtualKeyboard UI

Bug:  864826 
Change-Id: Ia594cc934f7c66121ff84660bd1039c5e05213d1
Reviewed-on: https://chromium-review.googlesource.com/1176463
Commit-Queue: Zach Helfinstein <zhelfins@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585292}
[modify] https://crrev.com/3019ca46a6050d6b64c198a6eadaca9ca83e3436/chrome/browser/resources/chromeos/switch_access/automation_manager.js
[modify] https://crrev.com/3019ca46a6050d6b64c198a6eadaca9ca83e3436/chrome/browser/resources/chromeos/switch_access/switch_access_predicate.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/acef8023bd1c3e5750b3e6ac4f6424a3c6d258b0

commit acef8023bd1c3e5750b3e6ac4f6424a3c6d258b0
Author: Anastasia Helfinstein <anastasi@google.com>
Date: Thu Dec 20 18:09:53 2018

Click virtual keyboard keys when selected with Switch Access.

Because the virtual keyboard's doDefault() behavior is to do nothing,
in order for Switch Access to type on the virtual keyboard we have to
send synthetic mouse events.

Bug:  864826 
Change-Id: Ie0562073d3f78baa42a9a6884dc41928922f2d4d
Reviewed-on: https://chromium-review.googlesource.com/c/1380340
Reviewed-by: David Tseng <dtseng@chromium.org>
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#618270}
[modify] https://crrev.com/acef8023bd1c3e5750b3e6ac4f6424a3c6d258b0/chrome/browser/resources/chromeos/switch_access/BUILD.gn
[modify] https://crrev.com/acef8023bd1c3e5750b3e6ac4f6424a3c6d258b0/chrome/browser/resources/chromeos/switch_access/manifest.json.jinja2
[modify] https://crrev.com/acef8023bd1c3e5750b3e6ac4f6424a3c6d258b0/chrome/browser/resources/chromeos/switch_access/navigation_manager.js
[add] https://crrev.com/acef8023bd1c3e5750b3e6ac4f6424a3c6d258b0/chrome/browser/resources/chromeos/switch_access/text_input_manager.js

With the above change to allow virtual keyboard keys to be pressed by Switch Access, the onscreen keyboard is now fully navigable by Switch Access.

Further improvements to keyboard interactions will be tracked under different bugs.