ChromeOS OOBE: Add ARIA-labels for OOBE screens.

chrome/browser/resources/chromeos/login/oobe_welcome.js

 // Copyright 2016 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 Polymer element for displaying material design OOBE.
  */
 
 Polymer({
   is: 'oobe-welcome-md',
 
   properties: {
     /**
      * Currently selected system language (display name).
      */
     currentLanguage: {
       type: String,
       value: '',
     },
 
     /**
+     * Currently selected input method (display name).
+     */
+    currentKeyboard: {
+      type: String,
+      value: '',
+    },
+
+    /**
      * List of languages for language selector dropdown.
      * @type {!Array<OobeTypes.LanguageDsc>}
      */
     languages: {
       type: Array,
+      observer: "onLanguagesChanged_",
     },
 
     /**
      * List of keyboards for keyboard selector dropdown.
      * @type {!Array<OobeTypes.IMEDsc>}
      */
     keyboards: {
       type: Array,
+      observer: "onKeyboardsChanged_",
     },
 
     /**
      * Flag that shows Welcome screen.
      */
     welcomeScreenShown: {
       type: Boolean,
       value: true,
     },
 
@@ skipping 63 matching lines @@
       value: '',
     },
 
     /**
      * True when connected to a network.
      * @private
      */
     isConnected_: {
       type: Boolean,
       value: false,
-    }
+    },
   },
 
   /** @override */
   ready: function() {
     CrOncStrings = {
       OncTypeCellular: loadTimeData.getString('OncTypeCellular'),
       OncTypeEthernet: loadTimeData.getString('OncTypeEthernet'),
       OncTypeVPN: loadTimeData.getString('OncTypeVPN'),
       OncTypeWiFi: loadTimeData.getString('OncTypeWiFi'),
       OncTypeWiMAX: loadTimeData.getString('OncTypeWiMAX'),
@@ skipping 254 matching lines @@
 
   /**
    * Handle language selection.
    *
    * @param {!{detail: {!OobeTypes.LanguageDsc}}} event
    * @private
    */
   onLanguageSelected_: function(event) {
     var item = event.detail;
     var languageId = item.value;
+    this.currentLanguage = item.title;
     this.screen.onLanguageSelected_(languageId);
   },
 
   /**
    * Handle keyboard layout selection.
    *
    * @param {!{detail: {!OobeTypes.IMEDsc}}} event
    * @private
    */
   onKeyboardSelected_: function(event) {
     var item = event.detail;
     var inputMethodId = item.value;
+    this.currentKeyboard = item.title;
     this.screen.onKeyboardSelected_(inputMethodId);
   },
 
+  onLanguagesChanged_: function() {
+    this.currentLanguage = Oobe.getSelectedTitle(this.languages);
+  },
+
+  onKeyboardsChanged_: function() {
+    this.currentKeyboard = Oobe.getSelectedTitle(this.keyboards);
+  },
+
   /**
    * Handle "OK" button for "LanguageSelection" screen.
    *
    * @private
    */
   closeLanguageSection_: function() {
     this.hideAllScreens_();
     this.welcomeScreenShown = true;
   },
 
@@ skipping 40 matching lines @@
    * @param {!{detail: {!OobeTypes.Timezone}}} event
    * @private
    */
   onTimezoneSelected_: function(event) {
     var item = event.detail;
     if (!item)
       return;
 
     this.screen.onTimezoneSelected_(item.value);
   },
+
+  /**
+    * This function formats message for labels.
+    * @param String label i18n string ID.
+    * @param String parameter i18n string parameter.
+    * @private
+    */
+  formatMessage_: function(label, parameter) {
+    return loadTimeData.getStringF(label, parameter);
+  },
 });