I am developing an extension for the Chrome browser with the API provided. I was just wondering if it is possible to place an app/extension (icon) in the notification area for easy access like the Google Hangouts app.
There is no public API for that. Hangouts is either using a private API or a native host module to achieve this.
Existing feature requests:
Extensions: https://code.google.com/p/chromium/issues/detail?id=72068 (in limbo)
Apps: https://code.google.com/p/chromium/issues/detail?id=142450 (seems implemented but not promoted to stable WontFix)
EDIT: The App API feature request is closed as WontFix. This is unlikely to be implemented.