Hide proxy settings when not connected at network select screen

chrome/browser/resources/chromeos/login/oobe_welcome.html

 <!-- 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. -->
 
 <link rel="import" href="chrome://resources/cr_elements/network/cr_network_icon.html">
 <link rel="import" href="chrome://resources/cr_elements/network/cr_network_select.html">
 <link rel="import" href="chrome://resources/cr_elements/network/cr_onc_types.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-iconset-svg/iron-iconset-svg.html">
@@ skipping 224 matching lines @@
       </hd-iron-icon>
       <div class="header">
         <h1 class="title" i18n-content="networkSectionTitle"></h1>
         <div class="subtitle" i18n-content="networkSectionHint"></div>
       </div>
       <div class="footer layout vertical">
         <cr-network-select id="networkSelect"
             on-default-network-changed="onDefaultNetworkChanged_"
             on-network-item-selected="onNetworkListNetworkItemSelected_"
             on-custom-item-selected="onNetworkListCustomItemSelected_"
-            custom-items="[[getNetworkCustomItems_()]]"
+            custom-items="[[getNetworkCustomItems_(isConnected_)]]"
             no-bottom-scroll-border
             class="focus-on-show">
         </cr-network-select>
       </div>
       <div class="bottom-buttons layout horizontal justified">
         <oobe-back-button on-tap="onNetworkSelectionBackButtonPressed_">
         </oobe-back-button>
         <oobe-next-button disabled="[[!isConnected_]]"
             on-tap="onSelectedNetworkConnected_">
         </oobe-next-button>
       </div>
     </oobe-dialog>
   </template>
 </dom-module>