Break joints of chicken.
Brush chicken with oil; season with salt and pepper.
Place, skin side down, in broiler pan .
Broil 5 to 6 inches from heat till lightly browned, about 20 minutes.
Turn; broil 15 to 20 minutes.
Meanwhile, in small saucepan combine sugar and cornstarch.
Stir in crushed pineapple, butter, soy sauce, and chopped onion.
Cook and stir till thickened and bubbly; cook 1 minute more.
Spoon glaze over chicken the last 5 minutes of broiling time.