Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 Patients are ineligible if administration of a live, attenuated vaccine within 4 weeks before randomization Administration of live vaccine within 4 weeks prior to study entry Treatment with a live, attenuated vaccine within 4 weeks before initiation of study treatment, or anticipation of need for such a vaccine during the course of the study Administration of a live, attenuated vaccine within 28 days prior to randomization or anticipation that such vaccine will be required during the study. Patients must agree not to receive live, attenuated influenza vaccine (e.g., FluMist) within 28 days prior to randomization, during treatment or within 5 months following the last dose of atezolizumab/placebo. Administration of a live attenuated vaccine within 4 weeks prior to initiation of study treatment or anticipation of need for such a vaccine during the study Administration of a live, attenuated vaccine within 4 weeks before Cycle 1 Day 1 Treatment with a live, attenuated vaccine within 4 weeks prior to initiation of study treatment, or anticipation of need for such a vaccine during the course of the study Patients should not receive immunization with attenuated live vaccine within one week of study entry or during study period Treatment with therapeutic oral or intravenous (IV) antibiotics; or with a live, attenuated vaccine; or systemic immunosuppressive medication Administration of a live, attenuated vaccine within 4 weeks prior to Cycle 1 Day 1 or at any time during the study and for at least 5 months after the last dose of study drug Receipt of a live, attenuated vaccine within 4 weeks prior to randomization or anticipation that such a live, attenuated vaccine will be required during the study Patients should not receive immunization with attenuated live vaccine within one week of study entry or during study period Immunization with any attenuated live vaccine within 1 week prior to initiating protocol-indicated treatment. Administration of a live vaccine within 4 weeks prior to study entry Receipt of a live, attenuated vaccine within 4 weeks prior to randomisation or anticipation that a live, attenuated vaccine will be required during atezolizumab/placebo treatment or within 5 months after the last dose of atezolizumab/placebo Administration of a live, attenuated vaccine within 4 weeks before cycle 1, day 1 or anticipation that such a live attenuated vaccine will be required during the study Administration of a live vaccine within 6 weeks of first dose of study drug Administration of a live vaccine within 4 weeks prior to start of protocol therapy Administration of a live, attenuated vaccine within 4 weeks for first study treatment Live, attenuated vaccine within 30 days prior to the first dose of protocol therapy Has received a live attenuated vaccine within 30 days prior to enrolling in the study. Administration of a live, attenuated vaccine within 4 weeks prior to enrollment or anticipation that such a live attenuated vaccine will be required during the study Administration of a live vaccine within 6 weeks of first dose of study drug Administration of a live, attenuated vaccine within 4 weeks prior to randomization or anticipation that such vaccine will be required during the study\r\n* Patients must agree not to receive live, attenuated influenza vaccine (e.g., FluMist) within 4 weeks prior to randomization, during treatment or within 5 months following the last dose of atezolizumab/placebo Live, attenuated vaccine within 30 days prior to day 1 of protocol therapy Administration of a live, attenuated vaccine within 4 weeks of Cycle 1, Day 1 or anticipation that such a live attenuated vaccine will be required during the study Patients who receive a live attenuated vaccine =< 28 days prior to registration are not eligible Administration of a live, attenuated vaccine within 4 weeks of the start of treatment or anticipation that such a live, attenuated vaccine will be required during the study Immunization with a live/attenuated vaccine within 30 days of enrollment Administration of a live, attenuated vaccine within 4 weeks before first dosing or during the study. Has received live, attenuated vaccine within 30 days prior to Study Day 1 Patient who requires live vaccine administration Subject has received a live, attenuated vaccine within 28 days prior to Cycle 1 Day 1; Receipt of a live, attenuated vaccine within 4 weeks prior to randomization or anticipation that such a live, attenuated vaccine will be required during the study Has received live, attenuated vaccine within 30 days prior to Study Day 1 Treatment with a live vaccine or a live, attenuated vaccine (e.g., nasal spray of live attenuated influenza vaccine or FluMistĀ®) within 4 weeks prior to initiation of study drug or anticipation that such treatment will be required during the study or within 5 months after the final dose of study drug Treatment with a live, attenuated vaccine within 4 weeks prior to initiation of study treatment, or anticipation of need for such a vaccine during the course of the study, or up to 5 months following the anticipated last dose of atezolizumab Administration of a live, attenuated vaccine within 4 weeks prior to enrollment Live attenuated vaccine within 4 weeks of study drug Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 or anticipation that such a live, attenuated vaccine will be required during the study Administration of attenuated vaccine within 4 weeks before enrollment Administration of a live, attenuated vaccine within 4 weeks prior to randomization Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 Administration of a live, attenuated vaccine within 4 weeks before Cycle 1 Day 1 Exclusion Criteria Unique to Cobimetinib: Immunization with any attenuated live vaccine within 1 week prior to registration Administration of a live, attenuated vaccine within 30 days before first dose of study treatment. Administration of a live, attenuated vaccine within 4 weeks before cycle 1, day 1 or anticipation that such a live, attenuated vaccine will be required during the study Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 or anticipation that such a live attenuated vaccine will be required during the study Administration of a live/attenuated vaccine within 4 weeks prior to the first dose of study treatment, within 5 months following the administration of the last dose of study drug, or anticipation that such a live/attenuated vaccine will be required during the study Administration of live, attenuated vaccine within 8 weeks before the start of treatment (day 0) and throughout the study Administration of a live, attenuated vaccine within 4 weeks before cycle 1, day 1 or anticipation that such a live, attenuated vaccine will be required during the study Administration of live, attenuated vaccine within 8 weeks before the start of treatment (day 0) and throughout the study Any plan to receive a live attenuated vaccine during study treatment Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 or anticipation that such a live attenuated vaccine will be required during the study Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 or anticipation that such a live attenuated vaccine will be required during the study Immunization with a live/attenuated vaccine within 28 days prior to conditioning Administration of a live, attenuated vaccine within 4 weeks for first study treatment Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 or anticipation that such a live attenuated vaccine will be required during the study Immunization with a live, attenuated vaccine within 4 weeks prior to study enrollment Live attenuated vaccine within 4 weeks prior to first day of study treatment Receipt of a live, attenuated vaccine within 4 weeks prior to initiation of study drug (cycle 1, day 1 [C1D1]) or anticipation that such a live, attenuated vaccine will be required during the study Administration of a live, attenuated vaccine within 28 days before Day 1 or anticipation that such a live attenuated vaccine will be required during the study Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1