I saw a link http://dangercove.github.com/html5-notifications/. Here plain-text-type notification works in google chrome (version 23). But html-type notification is not working. I tested it in chromium browser (version 17). Both content-type are working. Why the html-type is not working in chrome?
HTML5 notifications with HTML have been deprecated:
Since this is draft it's all subject to change, such as you are experiencing now. I know, it's sad.