//description from Chrome Store:
//https://chromewebstore.google.com/detail/simpliest-notification-ch/ibocgdgnkbabcgfhianjfjgekagcdjjj
//previously https://chrome.google.com/webstore/detail/fbnotifier-low-memory/emlidomckbobabadfkjgblnkoglkmjak (blocked)
Simple button on your toolbar that checks, counts and shows number of all your Facebook notifications in your language.
And it's least memory-consuming of all such extensions available!
Clicking on the button takes you to your facebook homepage (or swithes you to facebook tab, if already opened).
And what's important – you can customize how often it should check for new notifications, completely as you want!