Enable per-word highlighting by default.

This will be launched in Chrome 65 (see launch bug).

Bug: 785018
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ifd26e1bbede7e21c547df51a5edc7397167a74b5
Reviewed-on: https://chromium-review.googlesource.com/813076Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532219}

chrome/browser/resources/chromeos/select_to_speak/select_to_speak.js

@@ -367,7 +367,7 @@ var SelectToSpeak = function() {
   this.speechPitch_ = 1.0;
 
   /** @private {boolean} */
-  this.wordHighlight_ = false;
+  this.wordHighlight_ = true;
 
   /** @const {string} */
   this.color_ = '#f73a98';
@@ -977,6 +977,9 @@ SelectToSpeak.prototype = {
                 }
                 if (prefs['wordHighlight'] !== undefined) {
                   this.wordHighlight_ = prefs['wordHighlight'];
+                } else {
+                  chrome.storage.sync.set(
+                      {'wordHighlight': this.wordHighlight_});
                 }
                 if (prefs['highlightColor']) {
                   this.highlightColor_ = prefs['highlightColor'];