config_service: add last import validation and tests

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 20 matching lines @@
         border-width: 2px;
         width: 40%;
         height: 100%;
         margin: auto;
       }
     </style>
 
     <iron-ajax
         auto
         id="requestConfigs"
-        url="/_ah/api/config/v1/config-sets"
+        url="/_ah/api/config/v1/config-sets?include_last_import_attempt=true"
         handle-as="json"
         on-response="_onGotConfigSets">
     </iron-ajax>
     
     <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)]]">
         <template is="dom-if" if="[[_isEmpty(searchResults)]]">
           <div class="center">No config sets found.</div>
         </template>
         <template is="dom-if" if="[[_not(_isEmpty(searchResults))]]">
           <template is="dom-repeat" items="[[searchResults]]" as="config">
-            <config-set-card name="[[config.config_set]]" on-tap="_handleClick"></config-set-card>
+            <config-set-card 
+                name="[[config.config_set]]" 
+                last-import-attempt="[[config.last_import_attempt.success]]" 
+                on-tap="_handleClick">
+            </config-set-card>
           </template>
         </template>
       </template>
     </div>
   </template>
 
   <script>
     Polymer({
       is: 'front-page',
 
@@ skipping 37 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>