[MD Bookmarks] Add undo/redo functionality to MD Bookmarks.

chrome/test/data/webui/md_bookmarks/command_manager_test.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.
 
 suite('<bookmarks-command-manager>', function() {
   var commandManager;
   var store;
   var lastCommand;
   var lastCommandIds;
 
@@ skipping 95 matching lines @@
     var key = cr.isMac ? 'Enter' : 'F2';
     var keyCode = cr.isMac ? 13 : 113;
 
     store.data.selection.items = new Set(['11']);
     store.notifyObservers();
 
     MockInteractions.pressAndReleaseKeyOn(document, keyCode, '', key);
     commandManager.assertLastCommand('edit', ['11']);
   });
 
+  test('undo and redo commands trigger', function() {
+    var undoModifier = cr.isMac ? 'meta' : 'ctrl';
+    var undoKey = 'z';
+    var redoModifier = cr.isMac ? ['meta', 'shift'] : 'ctrl'
+    var redoKey = cr.isMac ? 'z' : 'y';
+
+    MockInteractions.pressAndReleaseKeyOn(document, '', undoModifier, undoKey);
+    commandManager.assertLastCommand('undo');
+
+    MockInteractions.pressAndReleaseKeyOn(document, '', redoModifier, redoKey);
+    commandManager.assertLastCommand('redo');
+  });
+
   test('does not delete children at same time as ancestor', function() {
     var lastDelete = null;
     chrome.bookmarkManagerPrivate.removeTrees = function(idArray) {
       lastDelete = idArray.sort();
     };
 
     var parentAndChildren = new Set(['1', '2', '12', '111']);
     assertTrue(commandManager.canExecute(Command.DELETE, parentAndChildren));
     commandManager.handle(Command.DELETE, parentAndChildren);
 
@@ skipping 115 matching lines @@
     assertOpenedTabs(['http://111/', 'http://12/']);
   });
 
   test('control-double click opens full selection', function() {
     customClick(items[0]);
     simulateDoubleClick(items[2], {ctrlKey: true});
 
     assertOpenedTabs(['http://111/', 'http://13/']);
   });
 });