The purpose of this study is to compare any good and bad effects of using the drug atezolizumab along with the usual chemotherapy compared to the usual chemotherapy alone. The addition of atezolizumab to the usual chemotherapy could prevent or reduce the chances of your cancer from returning, but it could also cause side effects. This study will allow the researchers to know whether this different approach is better, the same, or worse than the usual approach. To be better, the study drug would need to demonstrate increased chances of survival without the tumor returning by 10% or more compared to the usual approach. This drug, atezolizumab, is being tested in several types of cancer and has been granted FDA approval for its use in the treatment of bladder cancer. Atezolizumab is investigational for this study.