A Study Evaluating Safety and Efficacy of Obinutuzumab, Polatuzumab Vedotin (Pola), and Atezolizumab (Atezo) in Participants With Relapsed or Refractory Follicular Lymphoma (FL) and Rituximab, Atezo, and Pola in Participants With Relapsed or Refractory Diffuse Large B-Cell Lymphoma (DLBCL)

This study will evaluate the safety, efficacy, pharmacokinetics, and immunogenicity of obinutuzumab + Atezo + Pola in participants with relapsed or refractory (RR) FL and rituximab + Atezo + Pola in participants with RR DLBCL. The study will include an initial dose-escalation phase designed to determine the recommended Phase 2 dose (RP2D) for Pola in this treatment combination, followed by an expansion phase in which Pola will be given at the RP2D. All participants will receive induction treatment with obinutuzumab + Atezo + Pola for 6 cycles. RR FL participants achieving a complete response (CR), partial response (PR), or stable disease (SD) at the end of induction (EOI) will receive maintenance treatment with obinutuzumab.