MD WebUI: Add loading spinner to cr-toolbar, hook into MD History toolbar

chrome/browser/resources/md_history/app.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-pages/iron-pages.html">
 <link rel="import" href="chrome://history/grouped_list.html">
 <link rel="import" href="chrome://history/history_list.html">
 <link rel="import" href="chrome://history/history_toolbar.html">
 <link rel="import" href="chrome://history/synced_device_manager.html">
 <link rel="import" href="chrome://history/side_bar.html">
 <link rel="import" href="chrome://history/shared_style.html">
 <link rel="stylesheet" href="chrome://resources/css/md_colors.css">
@@ skipping 24 matching lines @@
       history-grouped-list {
         flex: 1 0 0;
       }
 
       #content {
         display: flex;
         flex: 1 0 0;
         overflow: hidden;
       }
     </style>
-    <history-toolbar id="toolbar" searching="[[queryState_.querying]]"
+    <history-toolbar id="toolbar"
+        spinner-active="[[shouldShowSpinner_(queryState_.querying,
+                                             queryState_.incremental,
+                                             queryState_.searchTerm)]]"
         is-grouped-mode="{{grouped_}}"
         grouped-range="{{queryState_.range}}"
         search-term="{{queryState_.searchTerm}}"
         query-start-time="[[queryState_.info.queryStartTime]]"
         query-end-time="[[queryState_.info.queryEndTime]]">
     </history-toolbar>
 
     <div id="main-container">
       <history-side-bar id="history-side-bar" selected-page="{{selectedPage_}}">
       </history-side-bar>
@@ skipping 12 matching lines @@
         <template is="dom-if" if="[[syncedTabsSelected_(selectedPage_)]]">
           <history-synced-device-manager id="history-synced-device-manager"
               session-list="[[queryState_.sessionList]]">
           </history-synced-device-manager>
         </template>
       </iron-pages>
     </div>
   </template>
   <script src="chrome://history/app.js"></script>
 </dom-module>