This randomized phase II trial studies how well carboplatin with or without atezolizumab works in treating patients with stage IV triple negative breast cancer. Drugs used in chemotherapy, such as carboplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Monoclonal antibodies, such as atezolizumab, may interfere with the ability of tumor cells to grow and spread. Giving carboplatin with atezolizumab may work better in treating patients with stage IV triple negative breast cancer