The fifth Chrome Dimension level can be unlocked from a chrome ‘egg’ found in Level 2-20. The egg in this one is a a bit hard to get. Because the white bird does not go as far as where the egg is, you will have to waste it. For the second bird (the yellow bird), you will have to shoot it at the steepest angle possible (up), and click it right after it starts shooting. If you do not hit the exact spot, play around with when you speed up the bird. This egg will take a couple of tries to get.
You should take a look at the Chrome Control guide for information on controlling the game. Here is a video demonstrating how to get the egg:
For your first hit, you want to take out the pig on the left. From there, use the second hit to weaken the structure. For your third hit, take out the right portion. For your last hit, take out the rest of the structure.