Saute first 4 ingredients in a large skillet coated with non-stick cooking spray over medium-high heat 5 minutes or until onion is tender. Add balsamic vinegar; cook 2 minutes more or until liquid is absorbed. Set aside.
Spread pesto over pizza crust. Sprinkle with mushroom mixture. Top with mozzarella cheese and tomatoes. Sprinkle with goat cheese and parmesan cheese.
Bake for 10 minutes or until edges are brown and cheese is melted.