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

chrome/browser/resources/md_bookmarks/command_manager.js

Index: chrome/browser/resources/md_bookmarks/command_manager.js
diff --git a/chrome/browser/resources/md_bookmarks/command_manager.js b/chrome/browser/resources/md_bookmarks/command_manager.js
index 7dbf8d0761bdc5483eb2c99414124e2efad14d2a..aef8c5ae9f941b70e76dec863e453070faf347f5 100644
--- a/chrome/browser/resources/md_bookmarks/command_manager.js
+++ b/chrome/browser/resources/md_bookmarks/command_manager.js
@@ -58,6 +58,9 @@ cr.define('bookmarks', function() {
           cr.isMac ? 'meta+enter' : 'ctrl+enter';
       this.shortcuts_[Command.OPEN_NEW_WINDOW] = 'shift+enter';
       this.shortcuts_[Command.OPEN] = cr.isMac ? 'meta+down' : 'enter';
+      this.shortcuts_[Command.UNDO] = cr.isMac ? 'meta+z' : 'ctrl+z';
+      this.shortcuts_[Command.REDO] =
+          cr.isMac ? 'meta+shift+z' : 'ctrl+y ctrl+shift+z';
     },
 
     detached: function() {
@@ -107,6 +110,9 @@ cr.define('bookmarks', function() {
       switch (command) {
         case Command.OPEN:
           return itemIds.size > 0;
+        case Command.UNDO:
+        case Command.REDO:
+          return true;
         default:
           return this.isCommandVisible_(command, itemIds) &&
               this.isCommandEnabled_(command, itemIds);
@@ -178,6 +184,12 @@ cr.define('bookmarks', function() {
                 // TODO(jiaxi): Add toast later.
               });
           break;
+        case Command.UNDO:
+          chrome.bookmarkManagerPrivate.undo();
+          break;
+        case Command.REDO:
+          chrome.bookmarkManagerPrivate.redo();
+          break;
         case Command.OPEN_NEW_TAB:
         case Command.OPEN_NEW_WINDOW:
         case Command.OPEN_INCOGNITO: