It’s very likely that chromebooks will in the near future get an update with a new notification center. François Beaufort shared a post on Google+ with screenshot, which shows us a collapsible notification rising from the new pinned icon from start menu. Contains any circles updates, messages, albums, missed calls and other things shared with you. As you can recognize, that icon looks like the Google+ Messenger icon.
Each of showed notification has in the top right corner an cross “button”. There are smaller and bigger types of allerts, but both of them contains image and text. Missed call notification provides “call back” and “send message” functions. At the bottom is “settings” and “clear all” button.
If Google will combine this with their Google Now function, it could be very interesting for Android and Google “ecosystem” users.