MD Settings: reduce complexity and overhead of Languages singleton

chrome/browser/resources/settings/languages_page/languages_page.js

 // Copyright 2015 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-languages-page' is the settings page
  * for language and input method settings.
  */
 (function() {
 'use strict';
@@ skipping 25 matching lines @@
       type: String,
       value: 'Placeholder, e.g. English (United States)',
     },
 
     /**
      * The language to display the details for.
      * @type {!LanguageState|undefined}
      * @private
      */
     detailLanguage_: Object,
-
-    /** @private {!LanguageHelper} */
-    languageHelper_: Object,
-  },
-
-  /** @override */
-  created: function() {
-    this.languageHelper_ = LanguageHelperImpl.getInstance();
   },
 
   /**
    * Handler for clicking a language on the main page, which selects the
    * language as the prospective UI language on Chrome OS and Windows.
    * @param {!Event} e The tap event.
    */
   onLanguageTap_: function(e) {
     // Only change the UI language on platforms that allow it.
     if ((!cr.isChromeOS && !cr.isWindows) || loadTimeData.getBoolean('isGuest'))
       return;
 
     // Set the prospective UI language. This won't take effect until a restart.
     var tapEvent = /** @type {!{model: !{item: !LanguageState}}} */(e);
-    if (tapEvent.model.item.language.supportsUI)
-      this.languageHelper_.setUILanguage(tapEvent.model.item.language.code);
+    if (tapEvent.model.item.language.supportsUI) {
+      settings.LanguageHelperImpl.getInstance().setUILanguage(
+          tapEvent.model.item.language.code);
+    }
   },
 
   /**
    * Stops tap events on the language options menu, its trigger, or its items
    * from bubbling up to the language itself. Tap events on the language are
    * handled in onLanguageTap_.
    * @param {!Event} e The tap event.
    */
   stopPropagationHandler_: function(e) {
     e.stopPropagation();
   },
 
   /**
    * Handler for enabling or disabling spell check.
    * @param {!{target: Element, model: !{item: !LanguageState}}} e
    */
   onSpellCheckChange_: function(e) {
-    this.languageHelper_.toggleSpellCheck(e.model.item.language.code,
-                                          e.target.checked);
+    settings.LanguageHelperImpl.getInstance().toggleSpellCheck(
+        e.model.item.language.code, e.target.checked);
   },
 
   /** @private */
   onBackTap_: function() {
     this.$.pages.back();
   },
 
   /**
    * Opens the Manage Languages page.
    * @private
@@ skipping 32 matching lines @@
   isHelpTextHidden_: function(change) {
     return this.languages.enabled.length <= 1;
   },
 
   /**
    * Moves the language up in the list.
    * @param {!{model: !{item: !LanguageState}}} e
    * @private
    */
   onMoveUpTap_: function(e) {
-    this.languageHelper_.moveLanguage(e.model.item.language.code, -1);
+    settings.LanguageHelperImpl.getInstance().moveLanguage(
+        e.model.item.language.code, -1);
   },
 
   /**
    * Moves the language down in the list.
    * @param {!{model: !{item: !LanguageState}}} e
    * @private
    */
   onMoveDownTap_: function(e) {
-    this.languageHelper_.moveLanguage(e.model.item.language.code, 1);
+    settings.LanguageHelperImpl.getInstance().moveLanguage(
+        e.model.item.language.code, 1);
   },
 
   /**
    * Opens the Language Detail page for the language.
    * @param {!{model: !{item: !LanguageState}}} e
    * @private
    */
   onShowLanguageDetailTap_: function(e) {
     this.detailLanguage_ = e.model.item;
     settings.navigateTo(settings.Route.LANGUAGES_DETAIL);
@@ skipping 15 matching lines @@
    *           target: !{tagName: string}}} e
    */
   onInputMethodTap_: function(e) {
     assert(cr.isChromeOS);
 
     // Taps on the paper-icon-button are handled in onInputMethodOptionsTap_.
     if (e.target.tagName == 'PAPER-ICON-BUTTON')
       return;
 
     // Set the input method.
-    this.languageHelper_.setCurrentInputMethod(e.model.item.id);
+    settings.LanguageHelperImpl.getInstance().setCurrentInputMethod(
+        e.model.item.id);
   },
 
   /**
    * Opens the input method extension's options page in a new tab (or focuses
    * an existing instance of the IME's options).
    * @param {!{model: !{item: chrome.languageSettingsPrivate.InputMethod}}} e
    * @private
    */
   onInputMethodOptionsTap_: function(e) {
     assert(cr.isChromeOS);
-    this.languageHelper_.openInputMethodOptions(e.model.item.id);
+    settings.LanguageHelperImpl.getInstance().openInputMethodOptions(
+        e.model.item.id);
   },
 
   /**
    * Returns the secondary text for the spell check subsection based on the
    * enabled spell check languages, listing at most 2 languages.
    * @return {string}
    * @private
    */
   getSpellCheckSecondaryText_: function() {
     var enabledSpellCheckLanguages =
@@ skipping 42 matching lines @@
    * language to use in Chrome) matches the current language. This pref is only
    * on Chrome OS and Windows; we don't control the UI language elsewhere.
    * @param {string} languageCode The language code identifying a language.
    * @param {string} prospectiveUILanguage The prospective UI language.
    * @return {boolean} True if the given language matches the prospective UI
    *     pref (which may be different from the actual UI language).
    * @private
    */
   isProspectiveUILanguage_: function(languageCode, prospectiveUILanguage) {
     assert(cr.isChromeOS || cr.isWindows);
-    return languageCode == this.languageHelper_.getProspectiveUILanguage();
+    return languageCode ==
+        settings.LanguageHelperImpl.getInstance().getProspectiveUILanguage();
   },
 
    /**
     * @return {string}
     * @private
     */
   getProspectiveUILanguageName_: function() {
-    return this.languageHelper_.getLanguage(
-        this.languageHelper_.getProspectiveUILanguage()).displayName;
+    var languageHelper = settings.LanguageHelperImpl.getInstance();
+    return languageHelper.getLanguage(
+        languageHelper.getProspectiveUILanguage()).displayName;
   },
 
   /**
    * Returns either the "selected" class, if the language matches the
    * prospective UI language, or an empty string. Languages can only be
    * selected on Chrome OS and Windows.
    * @param {string} languageCode The language code identifying a language.
    * @param {string} prospectiveUILanguage The prospective UI language.
    * @param {boolean} supportsUI Whether Chrome's UI can be shown in this
    *     language.
@@ skipping 50 matching lines @@
    * HACK(michaelpg): This is necessary to show the list when navigating to
    * the sub-page. Remove this function when PolymerElements/neon-animation#60
    * is fixed.
    * @param {string} tagName Name of the element containing the <iron-list>.
    */
   forceRenderList_: function(tagName) {
     this.$$(tagName).$$('iron-list').fire('iron-resize');
   },
 });
 })();