Google Chrome/Chromium browser has its own built in notifications for certain web apps, they look the same across all operating systems, but why not make it give you a default Ubuntu Unity / Gnome Shell notification instead?

There’s a simple extension properly support notify-osd notifications in Chrome. It will redirect Chrome’s Notification to Linux Native Notification, both support Ubuntu Unity desktop and GNOME Shell desktop, tested on both Ubuntu 11.10 and Ubuntu 12.04 (AMD64 and i386).

Install the extension on Chrome/Chromium:

In Chrome/Chromium web browser visit the official extension page.

Search and install the Linux Native Notification extension. Then manage it under chrome://chrome/extensions