Take 2 at browser_sync::ExtensionsActivityMonitor....

chrome/browser/extensions/extension_bookmarks_module.h

 // Copyright (c) 2009 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_BOOKMARKS_MODULE_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_BOOKMARKS_MODULE_H_
 
 #include <string>
 
 #include "base/singleton.h"
@@ skipping 51 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ExtensionBookmarkEventRouter);
 };
 
 class BookmarksFunction : public AsyncExtensionFunction,
                           public NotificationObserver {
   virtual void Run();
   virtual bool RunImpl() = 0;
 
  protected:
   // Helper to get the bookmark id as int64 from the given string id.
-  // Sets error_ to an errro string if the given id string can't be parsed
+  // Sets error_ to an error string if the given id string can't be parsed
   // as an int64. In case of error, doesn't change id and returns false.
   bool GetBookmarkIdAsInt64(const std::string& id_string, int64* id);
 
  private:
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
   NotificationRegistrar registrar_;
 };
 
@@ skipping 35 matching lines @@
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME("bookmarks.move")
 };
 
 class UpdateBookmarkFunction : public BookmarksFunction {
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME("bookmarks.update")
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_BOOKMARKS_MODULE_H_