Crock Pot Chicken Taco Chili

1 onion, chopped
1 16oz. black beans
1 16oz. kidney beans
1 8oz. tomato sauce
10 oz frozen corn kernels
2 14.5oz cans diced tomatos w/ green chilies
1 pkg. taco seasoning
1 T cumin
1 T chili powder
3-4 boneless chicken breast

Combine beans, onion, corn, tomato sauce, cumin, chili powder, diced tomatos and green chilies, and taco seasoning in slow cooker.    Place chicken on top and cover with lid.  Cook on low 10 hours or on high 6 hours.  Half hour b/f serving, remove chicken and shred.  Return chicken to slow cooker and stir in.  Top with fresh cilantro, cheese and sour cream!