Preheat Oven To 350 Degrees F (175 Degrees C). Stir Together The Cream Cheese, Margarine, Salt, Pepper, Milk, And Onion Together. Fold The Chicken Into The Cream Cheese Mixture. Separate Crescent Rolls Into 4 Rectangles And Smooth The Perforations. Spoon 1/2 Cup Of The Chicken Mixture Into The Center Of Each Rectangle. Fold The Corners Over The Chicken Mixture And Pinch Along The Edges To Seal Into A Ball Shape. Arrange On A Baking Sheet. Sprinkle Bread Crumbs Over The Top Of The Newly Formed 'Baseballs.' Bake In Preheated Oven Until Browned, About 20 Minutes.