[MD History] Make sidebar menu respond to spacebar.

chrome/browser/resources/md_history/side_bar.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-side-bar',
 
+  behaviors: [Polymer.IronA11yKeysBehavior],
+
   properties: {
     selectedPage: {type: String, notify: true},
 
     route: Object,
 
     showFooter: Boolean,
 
     // If true, the sidebar is contained within an app-drawer.
     drawer: {type: Boolean, reflectToAttribute: true},
   },
 
+  keyBindings: {
+    'space:keydown': 'onSpacePressed_',
+  },
+
+  /**
+   * @param {CustomEvent} e
+   * @private
+   */
+  onSpacePressed_: function(e) {
+    e.detail.keyboardEvent.path[0].click();
+  },
+
   /**
    * @private
    */
   onSelectorActivate_: function() { this.fire('history-close-drawer'); },
 
   /**
    * Relocates the user to the clear browsing data section of the settings page.
    * @param {Event} e
    * @private
    */
   onClearBrowsingDataTap_: function(e) {
     var browserService = md_history.BrowserService.getInstance();
     browserService.recordAction('InitClearBrowsingData');
     browserService.openClearBrowsingData();
     e.preventDefault();
   },
 
   /**
    * @param {Object} route
    * @private
    */
   getQueryString_: function(route) { return window.location.search; }
 });