Select-to-Speak should only use voices with required event types.

Some voices are missing callbacks Select-to-Speak needs. Those voices
shouldn't be displayed to the user in Select-to-Speak settings, or
available from select-to-speak at all.

Bug: 822440
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: If998f430fcc0854052b7d9bb1ed89c41b0069fb8
Reviewed-on: https://chromium-review.googlesource.com/967266Reviewed-by: David Tseng <dtseng@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544093}

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

@@ -944,9 +944,15 @@ SelectToSpeak.prototype = {
           if (voices.length == 0)
             return;
 
-          voices.forEach((function(voice) {
+          voices.forEach((voice) => {
+            if (!voice.eventTypes.includes('start') ||
+                !voice.eventTypes.includes('end') ||
+                !voice.eventTypes.includes('word') ||
+                !voice.eventTypes.includes('cancelled')) {
+              return;
+            }
             this.validVoiceNames_.add(voice.voiceName);
-                         }).bind(this));
+          });
 
           voices.sort(function(a, b) {
             function score(voice) {

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

@@ -96,6 +96,13 @@ SelectToSpeakOptionsPage.prototype = {
       voices.forEach(function(voice) {
         if (!voice.voiceName)
           return;
+        if (!voice.eventTypes.includes('start') ||
+            !voice.eventTypes.includes('end') ||
+            !voice.eventTypes.includes('word') ||
+            !voice.eventTypes.includes('cancelled')) {
+          // Required event types for Select-to-Speak.
+          return;
+        }
         var option = document.createElement('option');
         option.voiceName = voice.voiceName;
         option.innerText = option.voiceName;