What does getting the Chrome icon in Angry Birds Chrome Edition do?
Solution 1:
This unlocks the sixth "Chrome Dimension Level". So yeah, you got a bonus level :). The Chrome Dimension appears as an episode (set of levels) in the main menu area of the game.
Check out another of my answers if you want to see the locations of the other Chrome Dimension pickups and how to get them.
Solution 2:
I had that happen on 4 of them. Im guessing since I now have 3 stars on all the levels and only got 3 of the chrome dimensions unlocked but all the chrome icons are gone because I failed the level when I got those icons and I haven't found another way to get them... yup we've missed out. I now have to wait for new friends to join before I get any new levels to play.