MD Bookmarks: Implement item selection in new data flow system

chrome/browser/resources/md_bookmarks/util.js

 // Copyright 2017 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.
 
 /**
  * @fileoverview Utility functions for the Bookmarks page.
  */
 
 cr.define('bookmarks.util', function() {
   /**
@@ skipping 42 matching lines @@
   function createEmptyState() {
     return {
       nodes: {},
       selectedFolder: '0',
       closedFolders: {},
       search: {
         term: '',
         inProgress: false,
         results: [],
       },
+      selection: {
+        items: {},
+        anchor: null,
+      },
     };
   }
 
   return {
     createEmptyState: createEmptyState,
     getDisplayedList: getDisplayedList,
     normalizeNodes: normalizeNodes,
   };
 });