A Study of Obinutuzumab in Combination With CHOP Chemotherapy Versus Rituximab With CHOP in Participants With CD20-Positive Diffuse Large B-Cell Lymphoma (GOYA)

Inclusion Criteria:

Previously untreated CD20-positive DLBCL
At least 1 bi-dimensionally measurable lesion (greater than [>]1.5 centimeters [cm] in its largest dimension on the computed tomography [CT] scan)
Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2
Adequate hematological function
Low-intermediate, high-intermediate or high-risk International Prognostic Index (IPI) score (low-risk IPI score: IPI 1 irrespective of bulky disease or IPI 0 with bulky disease, defined as one lesion greater than equal to (>/=) 7.5 cm)
Left ventricular ejection fraction (LVEF) >/=50 percent (%) on cardiac multiple-gated acquisition (MUGA) scan or cardiac echocardiogram

Exclusion Criteria:

History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies or known sensitivity or allergy to murine products or to any component of CHOP or obinutuzumab
Contraindication to any of the individual components of CHOP, including prior receipt of anthracyclines
Participants with transformed lymphoma and participants with follicular lymphoma IIIB
Prior therapy for DLBCL, with the exception of nodal biopsy or local irradiation
Prior treatment with cytotoxic drugs or rituximab for another condition (for example, rheumatoid arthritis) or prior use of an anti-CD20 antibody
Prior use of any monoclonal antibody within 3 months of the start of Cycle 1
Corticosteroid use of >30 milligrams per day (mg/day) of prednisone or equivalent, for purposes other than lymphoma symptom control
Primary central nervous system (CNS) lymphoma and secondary CNS involvement by lymphoma, mantle-cell lymphoma (MCL), or histologic evidence of transformation to a Burkitt lymphoma, primary mediastinal DLBCL, primary effusion lymphoma, plasmablastic lymphoma, and primary cutaneous DLBCL