It's a 'classical' Italian method - 'pollo a la mattone'. Usually you marinate the chicken in a lemon/garlic/maybe rosemary, maybe oregano / olive oil marinade, then cooking the chicken under the brick (either stovetop or grill) is supposed to make the skin extra-cripsy and yummy, and the meat tender, as it cooks more quickly. I've been wanting to try it, just haven't gotten around to it. If you google 'chicken under a brick' you'll get lots of recipes.