Move auto-updater-win to ES6

lib/browser/api/auto-updater/auto-updater-win.js

@@ -1,33 +1,27 @@
 'use strict'
 
-const app = require('electron').app
-const EventEmitter = require('events').EventEmitter
+const {app} = require('electron')
+const {EventEmitter} = require('events')
 const squirrelUpdate = require('./squirrel-update-win')
-const util = require('util')
 
-function AutoUpdater () {
-  EventEmitter.call(this)
-}
-
-util.inherits(AutoUpdater, EventEmitter)
-
-AutoUpdater.prototype.quitAndInstall = function () {
+class AutoUpdater extends EventEmitter {
+  quitAndInstall () {
     if (!this.updateAvailable) {
       return this.emitError('No update available, can\'t quit and install')
     }
     squirrelUpdate.processStart()
     return app.quit()
-}
+  }
 
-AutoUpdater.prototype.getFeedURL = function () {
+  getFeedURL () {
     return this.updateURL
-}
+  }
 
-AutoUpdater.prototype.setFeedURL = function (updateURL, headers) {
+  setFeedURL (updateURL, headers) {
     this.updateURL = updateURL
-}
+  }
 
-AutoUpdater.prototype.checkForUpdates = function () {
+  checkForUpdates () {
     if (!this.updateURL) {
       return this.emitError('Update URL is not set')
     }
@@ -60,12 +54,13 @@ AutoUpdater.prototype.checkForUpdates = function () {
         })
       })
     })
-}
+  }
 
-// Private: Emit both error object and message, this is to keep compatibility
-// with Old APIs.
-AutoUpdater.prototype.emitError = function (message) {
+  // Private: Emit both error object and message, this is to keep compatibility
+  // with Old APIs.
+  emitError (message) {
     return this.emit('error', new Error(message), message)
+  }
 }
 
 module.exports = new AutoUpdater()