The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/80eddae997875f588e7d71a14a10f7775d74ab54

commit 80eddae997875f588e7d71a14a10f7775d74ab54
Author: Katie Dektar <katydek@google.com>
Date: Thu Dec 07 08:45:53 2017

Properly sets default highlight color in Select-to-Speak.

This fixes a bug where the first time you open the select-to-speak
settings page the highlight color drop-down doesn't have a color
selected.

Bug:  792728 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ic6f1653d8108e5d47fdc48c555eb55c0bbed51d8
Reviewed-on: https://chromium-review.googlesource.com/812426
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522383}
[modify] https://crrev.com/80eddae997875f588e7d71a14a10f7775d74ab54/chrome/browser/resources/chromeos/select_to_speak/select_to_speak.js

Google Chrome 67.0.3369.0 (Official Build) canary (64-bit)
Firmware Version Google_Samus.6300.276.0
Flag enabled: #enable-experimental-accessibility-features

In STS settings, word highlight color default is Blue. Other color options work as expected, color even changes in real time while STS is reading!