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

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-media-query/iron-media-query.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html">
 
 <dom-module id="cr-toolbar">
   <template>
     <style>
       :host {
         color: #fff;
         display: flex;
@@ skipping 28 matching lines @@
         display: none;
       }
     </style>
     <div id="leftContent">
       <h1>[[pageName]]</h1>
     </div>
 
     <div id="centeredContent">
       <cr-toolbar-search-field id="search" narrow="[[narrow_]]"
           label="[[searchPrompt]]" clear-label="[[clearLabel]]"
+          spinner-active="[[spinnerActive]]"
           showing-search="{{showingSearch_}}">
       </cr-toolbar-search-field>
       <iron-media-query query="(max-width: 900px)" query-matches="{{narrow_}}">
       </iron-media-query>
     </div>
   </template>
   <script src="cr_toolbar.js"></script>
 </dom-module>