ChromeOS OOBE: Fix EULA Back button.

chrome/browser/resources/chromeos/login/oobe_welcome.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 Polymer element for displaying material design OOBE.
  */
 
 Polymer({
   is: 'oobe-welcome-md',
@@ skipping 278 matching lines @@
   OpenAddMobileNetworkDialog_: function(item) {
     chrome.send('launchAddMobileNetworkDialog');
   },
 
   /**
    * This is called when network setup is done.
    *
    * @private
    */
   onSelectedNetworkConnected_: function() {
+    this.networkLastSelectedGuid_ = '';
     chrome.send('login.NetworkScreen.userActed', ['continue']);
   },
 
   /**
    * This gets called whenever the default network changes.
    * @param {!{detail: ?CrOnc.NetworkStateProperties}} event
    * @private
    */
   onDefaultNetworkChanged_: function(event) {
     var state = event.detail;
@@ skipping 159 matching lines @@
   /**
     * This function formats message for labels.
     * @param String label i18n string ID.
     * @param String parameter i18n string parameter.
     * @private
     */
   formatMessage_: function(label, parameter) {
     return loadTimeData.getStringF(label, parameter);
   },
 });