MD Bookmarks: Add right-click context menu to sidebar folders

chrome/test/data/webui/md_bookmarks/test_command_manager.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.
 
 /**
  * Creates and returns a CommandManager which tracks what commands are executed.
  * @constructor
  * @extends {bookmarks.CommandManager}
  */
 function TestCommandManager() {
   var commandManager = document.createElement('bookmarks-command-manager');
   var lastCommand = null;
   var lastCommandIds = null;
 
   var realHandle = commandManager.handle.bind(commandManager);
   commandManager.handle = function(command, itemIds) {
     lastCommand = command;
     lastCommandIds = itemIds;
     realHandle(command, itemIds);
   };
 
-  commandManager.assertLastCommand = function (command, ids) {
+  /**
+   * @param {Command} command
+   * @param {!Array<string>} ids
+   */
+  commandManager.assertLastCommand = function(command, ids) {
     assertEquals(command, lastCommand);
     if (ids)
       assertDeepEquals(ids, normalizeSet(lastCommandIds));
     lastCommand = null;
     lastCommandIds = null;
   };
 
+  /** @param {!Array<string>} ids */
+  commandManager.assertMenuOpenForIds = function(ids) {
+    assertDeepEquals(ids, normalizeSet(commandManager.menuIds_));
+  };
+
   return commandManager;
 }