A Study of the Combination of Ibrutinib Plus Venetoclax Versus Chlorambucil Plus Obinutuzumab for the First-line Treatment of Participants With Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL)

Inclusion Criteria:

Adult participants who are: (a) greater than or equal to (>=) 65 years old or, (b) 18 to 64 years old and have at least 1 of the following:

Cumulative Illness Rating Scale (CIRS) score > 6
Creatinine clearance (CrCl) estimated less than (<) 70 milliliter per minute (mL/min) using Cockcroft-Gault equation
Diagnosis of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) that meets International Workshop on Chronic Lymphocytic Leukemia (iwCLL) criteria
Measurable nodal disease (by computed tomography [CT]), defined as at least one lymph node > 1.5 centimeter (cm) in longest diameter
Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) Grade less than or equal to (<=) 2
Active CLL/SLL requiring treatment per the iwCLL criteria

Exclusion Criteria:

Prior anti-leukemic therapy for CLL or SLL
Presence of deletion of the short arm of chromosome 17 (del17p) or known TP53 mutation detected at a threshold of >10 percent (%) variable allele frequency (VAF)
Major surgery within 4 weeks of first dose of study treatment
Known bleeding disorders (example, von Willebrand's disease or hemophilia)
Central nervous system (CNS) involvement or suspected Richter's syndrome