Heat oil in large skillet on medium-high heat. Add chicken; cook and stir 5 minutes or until lightly browned.
Stir in corn, tomato sauce, chiles, chili powder and onion powder. Bring to boil. Reduce heat to medium-low; cook 10 minutes, stirring occasionally.
To serve, spoon chicken mixture over tortilla chips. Sprinkle with cheese and green onions. Serve with sour cream, if desired.