A Study of Atezolizumab in Combination With Either Obinutuzumab Plus Bendamustine or Obinutuzumab Plus (+) Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone (CHOP) in Participants With Follicular Lymphoma (FL) or Rituximab + CHOP in Participants With Diffuse Large B-Cell Lymphoma (DLBCL)

Inclusion Criteria:

- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2

- For participants enrolled in the safety run-in phase: lymphoma classified as either
relapsed or refractory FL after treatment with at least one prior chemoimmunotherapy
regimen or previously untreated Grade 1, 2, or 3a FL that requires treatment

- For participants enrolled in the expansion phase: lymphoma classified as either
previously untreated Grade 1, 2, or 3a FL that requires treatment or previously
untreated advanced DLBCL

- Histologically documented cluster of differentiation 20 (CD20) positive lymphoma

- Fluorodeoxyglucose-avid lymphoma

- At least one bi-dimensionally measurable lesion (greater than [>] 1.5 centimeters in
its largest dimension by CT scan or magnetic resonance imaging)

- Availability of a representative tumor specimen and the corresponding pathology report
for retrospective central confirmation of the diagnosis of FL or DLBCL

- For women who are not postmenopausal or surgically sterile: agreement to remain
abstinent (refrain from heterosexual intercourse) or use contraceptive methods that
result in a failure rate of less than [<] 1 percent [%] per year during the treatment
period and for at least 18 months after the last dose of study treatment for
participants in the Atezo-G-benda and Atezo-G-CHOP treatment groups or for at least 12
months after the last dose of study treatment for participants in the Atezo-R-CHOP
treatment group

- For men: agreement to remain abstinent or use contraceptive measures and agreement to
refrain from donating sperm

Exclusion Criteria:

- Histological evidence of transformation of FL into high-grade B-cell non-Hodgkin's
lymphoma (NHL)

- Central nervous system lymphoma or leptomeningeal infiltration

- For participants with DLBCL: preplanned consolidative radiotherapy

- Treatment with systemic immunosuppressive medications, including, but not limited to,
prednisone, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor
agents within 2 weeks prior to Day 1 of Cycle 1

- For participants with relapsed or refractory FL: prior allogeneic or autologous stem
cell transplantation, anthracycline therapy, treatment with fludarabine or alemtuzumab
within 12 months prior to Day 1 of Cycle 1, treatment with a monoclonal antibody,
radioimmunoconjugate, or antibody-drug conjugate within 4 weeks prior to Day 1 of
Cycle 1, radiotherapy, chemotherapy, hormonal therapy, or targeted small-molecule
therapy within 2 weeks prior to Day 1 of Cycle 1

- History of solid organ transplantation

- History of severe allergic or anaphylactic reaction or known sensitivity to humanized
or murine monoclonal antibodies

- Known hypersensitivity to biopharmaceuticals produced in Chinese hamster ovary cells
or any component of the atezolizumab, obinutuzumab, rituximab, or bendamustine
formulation, including mannitol

- Positive for hepatitis B surface antigen (HBsAg), total hepatitis B core antibody
(HBcAb), or hepatitis C virus (HCV) antibody at screening

- History of progressive multifocal leukoencephalopathy

- Vaccination with a live virus vaccine within 28 days prior to Day 1 of Cycle 1

- History of other malignancy, autoimmune disease, or any significant, uncontrolled
concomitant disease that could affect compliance with the protocol or interpretation
of results

- Major surgical procedure other than for diagnosis within 28 days prior to Day 1 of
Cycle 1, or anticipation of a major surgical procedure during the course of the study

- For participants who will be receiving CHOP: left ventricular ejection fraction (LVEF)
<50% by multiple-gated acquisition (MUGA) scan or echocardiogram

- Inadequate hematologic, renal, and liver function (unless due to underlying lymphoma)