[MD Bookmarks] Add UI for Material Bookmarks.

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',
+
+  properties: {
+    /** @type {BookmarkTreeNode} */
+    item: {
+      type: Object,
+      observer: 'onItemChanged_'
+    },
+
+    isFolder_: Boolean,
+  },
+
+  observers: [
+    'updateFavicon_(item.url)'
+  ],
+
+  /**
+   * @param {Event} e
+   * @private
+   */
+  onMenuButtonOpenTap_: function(e) {
+    this.fire('toggle-menu', {
+      target: e.target
+    });
+  },
+
+  /** @private */
+  onItemChanged_: function() {
+    this.isFolder_ = !(this.item.url);
+  },
+
+  /** @private */
+  updateFavicon_: function(url) {
+    this.$.icon.style.backgroundImage = cr.icon.getFavicon(url);
+  }
+});