MD Settings: reduce complexity and overhead of Languages singleton

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

Index: chrome/browser/resources/settings/languages_page/manage_input_methods_page.js
diff --git a/chrome/browser/resources/settings/languages_page/manage_input_methods_page.js b/chrome/browser/resources/settings/languages_page/manage_input_methods_page.js
index cb794f52b96ab95e98e6b7391070b128ec878d45..570901ec71b5b12101178259b67fc5b0ec038d57 100644
--- a/chrome/browser/resources/settings/languages_page/manage_input_methods_page.js
+++ b/chrome/browser/resources/settings/languages_page/manage_input_methods_page.js
@@ -39,11 +39,6 @@ Polymer({
     'enabledInputMethodsChanged_(languages.inputMethods.enabled.*)',
   ],
 
-  /** @override */
-  created: function() {
-    this.languageHelper_ = LanguageHelperImpl.getInstance();
-  },
-
   /** @private */
   availableInputMethodsChanged_: function() {
     this.populateLanguageList_();
@@ -64,9 +59,9 @@ Polymer({
     // TODO(michaelpg): Show confirmation dialog for 3rd-party IMEs.
     var id = e.model.item.id;
     if (e.target.checked)
-      this.languageHelper_.addInputMethod(id);
+      settings.LanguageHelperImpl.getInstance().addInputMethod(id);
     else
-      this.languageHelper_.removeInputMethod(id);
+      settings.LanguageHelperImpl.getInstance().removeInputMethod(id);
   },
 
   /**
@@ -81,14 +76,16 @@ Polymer({
     if (!targetInputMethod.enabled)
       return true;
 
+    var languageHelper = settings.LanguageHelperImpl.getInstance();
+
     // Third-party IMEs can always be removed.
-    if (!this.languageHelper_.isComponentIme(targetInputMethod))
+    if (!languageHelper.isComponentIme(targetInputMethod))
       return true;
 
     // Can be removed as long as there is another component IME.
     return this.languages.inputMethods.enabled.some(function(inputMethod) {
       return inputMethod != targetInputMethod &&
-          this.languageHelper_.isComponentIme(inputMethod);
+          languageHelper.isComponentIme(inputMethod);
     }, this);
   },
 
@@ -99,6 +96,7 @@ Polymer({
    */
   populateLanguageList_: function() {
     var languageList = [];
+    var languageHelper = settings.LanguageHelperImpl.getInstance();
 
     // Languages that have already been listed further up.
     var /** !Set<string> */ usedLanguages = new Set();
@@ -112,7 +110,7 @@ Polymer({
       // Skip the language if we have already included it or its base language.
       if (usedLanguages.has(languageState.language.code))
         continue;
-      var baseLanguageCode = this.languageHelper_.getLanguageCodeWithoutRegion(
+      var baseLanguageCode = languageHelper.getLanguageCodeWithoutRegion(
           languageState.language.code);
       if (usedLanguages.has(baseLanguageCode))
         continue;
@@ -122,7 +120,7 @@ Polymer({
       var languageFamilyCodes = [languageState.language.code];
       for (var j = i + 1; j < this.languages.enabled.length; j++) {
         var otherCode = this.languages.enabled[j].language.code;
-        if (this.languageHelper_.getLanguageCodeWithoutRegion(otherCode) ==
+        if (languageHelper.getLanguageCodeWithoutRegion(otherCode) ==
             baseLanguageCode) {
           languageFamilyCodes.push(this.languages.enabled[j].language.code);
         }
@@ -138,7 +136,7 @@ Polymer({
       // Add the language or base language.
       var displayLanguage = languageState.language;
       if (languageFamilyCodes.length > 1) {
-        var baseLanguage = this.languageHelper_.getLanguage(baseLanguageCode);
+        var baseLanguage = languageHelper.getLanguage(baseLanguageCode);
         if (baseLanguage)
           displayLanguage = baseLanguage;
       }
@@ -166,8 +164,9 @@ Polymer({
     /** @type {!Array<chrome.languageSettingsPrivate.InputMethod>} */
     var combinedInputMethods = [];
     for (var languageCode of languageCodes) {
-      var inputMethods = this.languageHelper_.getInputMethodsForLanguage(
-          languageCode);
+      var inputMethods =
+          settings.LanguageHelperImpl.getInstance().getInputMethodsForLanguage(
+              languageCode);
       // Get the language's unused input methods and mark them as used.
       var newInputMethods = inputMethods.filter(function(inputMethod) {
         if (usedInputMethods.has(inputMethod.id))