MD History: Only load needed paper-icon-buttons instead of whole set of icons

chrome/browser/resources/md_history/synced_device_card.js

 // 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.
 
 Polymer({
   is: 'history-synced-device-card',
 
   properties: {
     // Name of the synced device.
     device: {
@@ skipping 33 matching lines @@
     for (var i = 0; i < this.tabs.length; i++)
       window.open(this.tabs[i].url, '_blank');
   },
 
   /**
    * Toggles the dropdown display of synced tabs for each device card.
    */
   toggleTabCard: function() {
     this.$.collapse.toggle();
     this.$['dropdown-indicator'].icon =
-        this.$.collapse.opened ? 'expand-less' : 'expand-more';
+        this.$.collapse.opened ? 'cr:expand-less' : 'cr:expand-more';
   },
 
   /**
    * When the synced tab information is set, the icon associated with the tab
    * website is also set.
    * @private
    */
   updateIcons_: function() {
     this.async(function() {
       var icons = Polymer.dom(this.root).querySelectorAll('.website-icon');
 
       for (var i = 0; i < this.tabs.length; i++) {
         icons[i].style.backgroundImage =
             cr.icon.getFaviconImageSet(this.tabs[i].url);
       }
     });
   }
 });