MD Settings: Convert all browser proxies to use ES6 class syntax.

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

 // Copyright 2017 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 A helper object used from the languages section
  * to interact with the browser.
  */
 
 cr.define('settings', function() {
   /** @interface */
-  function LanguagesBrowserProxy() {}
-
-  LanguagesBrowserProxy.prototype = {
+  class LanguagesBrowserProxy {
     // <if expr="chromeos or is_win">
     /**
      * Sets the prospective UI language to the chosen language. This won't
      * affect the actual UI language until a restart.
      * @param {string} languageCode
      */
-    setProspectiveUILanguage: function(languageCode) {},
+    setProspectiveUILanguage(languageCode) {}
 
     /** @return {!Promise<string>} */
-    getProspectiveUILanguage: function() {},
+    getProspectiveUILanguage() {}
+
     // </if>
 
     /** @return {!LanguageSettingsPrivate} */
-    getLanguageSettingsPrivate: function() {},
+    getLanguageSettingsPrivate() {}
 
     // <if expr="chromeos">
     /** @return {!InputMethodPrivate} */
-    getInputMethodPrivate: function() {},
+    getInputMethodPrivate() {}
     // </if>
-  };
+  }
 
   /**
-   * @constructor
    * @implements {settings.LanguagesBrowserProxy}
    */
-  function LanguagesBrowserProxyImpl() {}
+  class LanguagesBrowserProxyImpl {
+    // <if expr="chromeos or is_win">
+    /** @override */
+    setProspectiveUILanguage(languageCode) {
+      chrome.send('setProspectiveUILanguage', [languageCode]);
+    }
+
+    /** @override */
+    getProspectiveUILanguage() {
+      return cr.sendWithPromise('getProspectiveUILanguage');
+    }
+
+    // </if>
+
+    /** @override */
+    getLanguageSettingsPrivate() {
+      return /** @type {!LanguageSettingsPrivate} */ (
+          chrome.languageSettingsPrivate);
+    }
+
+    // <if expr="chromeos">
+    /** @override */
+    getInputMethodPrivate() {
+      return /** @type {!InputMethodPrivate} */ (chrome.inputMethodPrivate);
+    }
+    // </if>
+  }
+
   // The singleton instance_ is replaced with a test version of this wrapper
   // during testing.
   cr.addSingletonGetter(LanguagesBrowserProxyImpl);
 
-  LanguagesBrowserProxyImpl.prototype = {
-    // <if expr="chromeos or is_win">
-    /** @override */
-    setProspectiveUILanguage: function(languageCode) {
-      chrome.send('setProspectiveUILanguage', [languageCode]);
-    },
-
-    /** @override */
-    getProspectiveUILanguage: function() {
-      return cr.sendWithPromise('getProspectiveUILanguage');
-    },
-    // </if>
-
-    /** @override */
-    getLanguageSettingsPrivate: function() {
-      return /** @type {!LanguageSettingsPrivate} */ (
-          chrome.languageSettingsPrivate);
-    },
-
-    // <if expr="chromeos">
-    /** @override */
-    getInputMethodPrivate: function() {
-      return /** @type {!InputMethodPrivate} */ (chrome.inputMethodPrivate);
-    },
-    // </if>
-  };
-
   return {
     LanguagesBrowserProxy: LanguagesBrowserProxy,
     LanguagesBrowserProxyImpl: LanguagesBrowserProxyImpl,
   };
 });