Cook the bacon in a large skillet over medium-low heat until crisp. With a slotted spoon, transfer it to a 4- to 6-quart slow cooker. Pour off all but a light coating of fat from the skillet. Add the chicken and brown over medium-high heat; transfer to the cooker.
Pour the wine into the skillet and scrape up any browned bits; add the skillet contents to the cooker, along with the mushrooms, onions, garlic, rosemary, and salt. Cover and cook on low heat for 6 hours, or on high for 3 hours.
Transfer the chicken, bacon, and vegetables to a platter; keep warm. Pour the sauce into a small saucepan. Combine the water and cornstarch; stir it into the sauce. Heat to boiling, stirring constantly, until the sauce thickens, about 5 minutes. Pour over the chicken.