Fix language switching

chrome/browser/resources/chromeos/chromevox/host/chrome/tts_background.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview Sends Text-To-Speech commands to Chrome's native TTS
  * extension API.
  *
  */
 
@@ skipping 39 matching lines @@
       this.propertyDefault['rate']);
   this.ttsProperties['pitch'] = (parseFloat(localStorage['pitch']) ||
       this.propertyDefault['pitch']);
   this.ttsProperties['volume'] = (parseFloat(localStorage['volume']) ||
       this.propertyDefault['volume']);
 
   // Use the current locale as the speech language if not otherwise
   // specified.
   if (this.ttsProperties['lang'] == undefined) {
     this.ttsProperties['lang'] =
-        chrome.i18n.getMessage('@@ui_locale').replace('_', '-');
+        chrome.i18n.getUILanguage();

[dmazzoni, 2016/11/17 22:49:38]

Did you confirm that this is in the right
format, i.e. with hyphens and not underscores,
and the same capitalization?

[David Tseng, 2016/11/17 23:03:02]

Yes, getMessage seems to be the outlier (xx_XX)

getUILanguage and getAcceptLanguage both return
xx-XX or xx

   }
 
   this.lastEventType = 'end';
 
   /** @private {number} */
   this.currentPunctuationEcho_ =
       parseInt(localStorage[cvox.AbstractTts.PUNCTUATION_ECHO] || 1, 10);
 
   /**
    * @type {!Array<{name:(string),
@@ skipping 606 matching lines @@
 
 
 /**
  * Update the current voice used to speak based upon values in storage. If that
  * does not succeed, fallback to use system locale when picking a voice.
  * @param {string} voiceName Voice name to set.
  * @private
  */
 cvox.TtsBackground.prototype.updateVoice_ = function(voiceName) {
   chrome.tts.getVoices(goog.bind(function(voices) {
-    var currentLocale = chrome.i18n.getMessage('@@ui_locale').replace('_', '-');
+    chrome.i18n.getAcceptLanguages(goog.bind(function(acceptLanguages) {
+      var currentLocale = acceptLanguages[0] ||

[dmazzoni, 2016/11/17 22:49:38]

Ideally we should use all acceptLanguages?
Maybe add a TODO

[David Tseng, 2016/11/17 23:03:02]

It's all kind of guess work at this point because I see the browser UI language
is different from the user's accept language and ChromeVox localized strings are
all based upon the ui locale (i.e. the extension resources).

We should definitely re-visit. Note the prsence of
chrome.i18n.detectLanguage
which we could use on a page to figure out which tts voice to use. I tried it
out and our engine is just too slow in switching to make it practical (not to
even begin considering how reliable the detection is).

+          chrome.i18n.getUILanguage() || '';
+      var match = voices.find.bind(voices);
+      var newVoice =
+          match(function(v) { return v.voiceName == voiceName; }) ||
+          match(function(v) { return v.lang === currentLocale; }) ||
+          match(function(v) { return currentLocale.startsWith(v.lang); }) ||
+          match(function(v) { return v.lang.startsWith(currentLocale); }) ||
+          voices[0];
 
-    // TODO(dtseng): Prefer voices having the default property once we switch to
-    // web speech. See crbug.com/544139.
-
-    var newVoice = voices.find(
-            function(v) { return v.voiceName == voiceName; }) ||
-        voices.find(function(v) { return v.lang === currentLocale; }) ||
-        voices.find(function(v) { return currentLocale.startsWith(v.lang); }) ||
-        voices[0];
-
-    if (newVoice) {
-      this.currentVoice = newVoice.voiceName;
-      this.startSpeakingNextItemInQueue_();
-    }
+      if (newVoice) {
+        this.currentVoice = newVoice.voiceName;
+        this.startSpeakingNextItemInQueue_();
+      }
+    }, this));
   }, this));
 };