[MD Bookmarks] Add draggable sidebar.

chrome/browser/resources/md_bookmarks/folder_node.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-folder-node',
 
   behaviors: [
     bookmarks.StoreClient,
   ],
@@ skipping 42 matching lines @@
   },
 
   /**
    * @private
    * @return {string}
    */
   getFolderIcon_: function() {
     return this.isSelectedFolder_ ? 'bookmarks:folder-open' : 'cr:folder';
   },
 
-  /**
-   * @private
-   * @return {string}
-   */
-  getArrowIcon_: function() {
-    return this.isClosed_ ? 'cr:arrow-drop-down' : 'cr:arrow-drop-up';
-  },
-
   /** @private */
   selectFolder_: function() {
     this.dispatch(bookmarks.actions.selectFolder(this.item_.id));
   },
 
   /**
    * Occurs when the drop down arrow is tapped.
    * @private
    */
   toggleFolder_: function() {
@@ skipping 38 matching lines @@
 
   /**
    * @param {string} itemId
    * @private
    * @return {boolean}
    */
   isFolder_: function(itemId) {
     return !this.getState().nodes[itemId].url;
   }
 });