Preheat oven to 350°. Combine chicken and barbecue sauce and wrap in foil, making a pouch. Heat chicken in oven 15 minutes. Set rolls on rack in oven with chicken until both are hot, 5 minutes.
Meanwhile, in a medium bowl, combine spinach, corn, cheddar cheese, onion, and vinaigrette. Split rolls, keeping 1 side attached. Fill with chicken mixture, then spinach salad.
Note: Nutritional analysis is per serving.