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

chrome/test/data/webui/md_bookmarks/command_manager_test.js

Index: chrome/test/data/webui/md_bookmarks/command_manager_test.js
diff --git a/chrome/test/data/webui/md_bookmarks/command_manager_test.js b/chrome/test/data/webui/md_bookmarks/command_manager_test.js
index e4d82eada7f8d280359a0ffcf5bd656b2f40c723..a862fbd33df4ada5562e57bc40ffb99fad55bae6 100644
--- a/chrome/test/data/webui/md_bookmarks/command_manager_test.js
+++ b/chrome/test/data/webui/md_bookmarks/command_manager_test.js
@@ -113,6 +113,19 @@ suite('<bookmarks-command-manager>', function() {
     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) {