MD Settings: Enable to search "Add languages" list.

chrome/browser/resources/settings/languages_page/add_languages_dialog.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 'settings-add-languages-dialog' is a dialog for enabling
  * languages.
  */
 Polymer({
   is: 'settings-add-languages-dialog',
@@ skipping 12 matching lines @@
     languagesToAdd_: {
       type: Object,
       value: function() { return new Set(); },
     },
 
     /** @private */
     disableActionButton_: {
       type: Boolean,
       value: true,
     },
+
+    /** @private */
+    filterValue_: {
+      type: String,
+      value: '',
+    },
   },
 
   attached: function() {
     this.$.dialog.showModal();
     // Fire iron-resize after the list initially displays to prevent flickering.
     setTimeout(function() {
       this.$$('iron-list').fire('iron-resize');
     }.bind(this));
   },
 
   /**
-   * Returns the supported languages that are not yet enabled, based on
+   * Returns the supported languages that are not yet enabled
+   * and matching with filter keyword, based on
    * the LanguageHelper's enabled languages list.
    * @param {!Array<!chrome.languageSettingsPrivate.Language>}
    *     supportedLanguages
    * @param {!Object} enabledLanguagesChange Polymer change record for
    *     |enabledLanguages|.
+   * @param {string} filterValue Keyword to filter languages in
+   *     supported languages.
    * @return {!Array<!chrome.languageSettingsPrivate.Language>}
    * @private
    */
-  getAvailableLanguages_: function(supportedLanguages, enabledLanguagesChange) {
+  getAvailableLanguages_: function(supportedLanguages,
+                                   enabledLanguagesChange,
+                                   filterValue) {
     return supportedLanguages.filter(function(language) {
-      return !this.languageHelper.isLanguageEnabled(language.code);
+      var isAvailableLanguage =
+          !this.languageHelper.isLanguageEnabled(language.code);
+      if (!filterValue) {
+        return isAvailableLanguage;
+      } else {
+        return isAvailableLanguage &&
+            Boolean(~language.displayName.indexOf(filterValue));

[michaelpg, 2016/12/02 03:56:41]

the ~ trick is a bit too clever; much more readable to just do:

  language.displayName.includes(filterValue)

[michaelpg, 2016/12/02 03:56:41]

This comparison should be case-insensitive (e.g. convert everything to
lowercase), so a lowercase search can return capitalized languages and vice
versa.

+      }
     }.bind(this));
   },
 
   /**
    * True if the user has chosen to add this language (checked its checkbox).
    * @return {boolean}
    * @private
    */
   willAdd_: function(languageCode) {
     return this.languagesToAdd_.has(languageCode);
@@ skipping 27 matching lines @@
   /**
    * Enables the checked languages.
    * @private
    */
   onActionButtonTap_: function() {
     this.$.dialog.close();
     for (var languageCode of this.languagesToAdd_)
       this.languageHelper.enableLanguage(languageCode);
   },
 });