config_service: Add authentication to the UI.

appengine/config_service/ui/src/config-ui/front-page.html

 <!--
   Copyright 2017 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 -->
 
 <link rel="import" href="../../bower_components/app-layout/app-layout.html">
 <link rel="import" href="../../bower_components/iron-ajax/iron-ajax.html">
 <link rel="import" href="../../bower_components/paper-button/paper-button.html">
 <link rel="import" href="../../bower_components/paper-search/paper-search-bar.html">
@@ skipping 17 matching lines @@
 
       paper-search-bar {
         border-style: solid;
         border-width: 2px;
         width: 40%;
         height: 100%;
         margin: auto;
       }
     </style>
 
-    <iron-ajax
-        auto
-        id="requestConfigs"
-        url="/_ah/api/config/v1/config-sets"
-        handle-as="json"
-        on-response="_onGotConfigSets">
-    </iron-ajax>
+    <template is="dom-if" if="[[!hidden]]">
+      <iron-ajax
+          auto
+          id="requestConfigs"
+          url="/_ah/api/config/v1/config-sets"
+          handle-as="json"
+          on-response="_onGotConfigSets"
+          headers="{{auth_headers}}">
+      </iron-ajax>
+    </template>
     
     <div class="search-bar">
       <paper-search-bar query="{{query}}"></paper-search-bar>
     </div>
     
     <div class="config-list">
       <template is="dom-if" if="[[isLoading]]">
         <div class="center">Fetching config sets...</div>
       </template>
       <template is="dom-if" if="[[_not(isLoading)]]">
@@ skipping 53 matching lines @@
         this.searchResults = this.configSetList.filter(e => e.config_set.includes(this.query));
       },
 
       _handleClick: function(event) {
         window.location = window.location.href + event.model.config.config_set;
       },
 
     });
   </script>
 </dom-module>