A Study of Tiragolumab Plus Atezolizumab Compared With Placebo Plus Atezolizumab in Participants With Completely Resected Non-small Cell Lung Cancer Who Have Received Adjuvant Platinum-based Chemotherapy

Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Histological or cytological diagnosis of Stage IIB, IIIA, and select IIIB NSCLC of either non-squamous or squamous histology * Participants must have had complete resection of NSCLC * Participants must have received between one to four cycles of adjuvant histology-based platinum doublet chemotherapy * Participants must have recovered adequately from surgery and from adjuvant chemotherapy * Tumor cell PD-L1 expression at \>/= 1% * Adequate hematologic and end-organ function. Exclusion Criteria: * Any history of prior NSCLC within the last 5 years * Any evidence of residual disease or disease recurrence following surgical resection of NSCLC, or during or following adjuvant chemotherapy * NSCLC known to have mutation in the epidermal growth factor receptor (EGFR) gene or an anaplastic lymphoma kinase (ALK) fusion oncogene