[MD Bookmarks] Add keyboard navigation and selection to bookmark list.

chrome/browser/resources/md_bookmarks/item.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: 'bookmarks-item',
 
   behaviors: [
     bookmarks.StoreClient,
   ],
@@ skipping 19 matching lines @@
     },
 
     /** @private */
     mouseFocus_: {
       type: Boolean,
       reflectToAttribute: true,
     },
 
     /** @private */
     isFolder_: Boolean,
-
-    /** @private */
-    openItemUrl_: String,
   },
 
   observers: [
     'updateFavicon_(item_.url)',
   ],
 
   listeners: {
     'mousedown': 'onMousedown_',
     'blur': 'onItemBlur_',
     'click': 'onClick_',
@@ skipping 67 matching lines @@
   onItemIdChanged_: function() {
     // TODO(tsergeant): Add a histogram to measure whether this assertion fails
     // for real users.
     assert(this.getState().nodes[this.itemId]);
     this.updateFromStore();
   },
 
   /** @private */
   onItemChanged_: function() {
     this.isFolder_ = !this.item_.url;
-    if (this.item_.url)
-      this.openItemUrl_ = this.item_.url;
-    else
-      this.openItemUrl_ = 'chrome://bookmarks/?id=' + this.itemId;
   },
 
   /**
    * @private
    */
   onMousedown_: function() {
     this.mouseFocus_ = true;
   },
 
   /**
@@ skipping 33 matching lines @@
   },
 
   /**
    * @param {string} url
    * @private
    */
   updateFavicon_: function(url) {
     this.$.icon.style.backgroundImage = cr.icon.getFavicon(url);
   },
 });