A Study of Atezolizumab in Combination With Carboplatin + Paclitaxel or Carboplatin + Nab-Paclitaxel Compared With Carboplatin + Nab-Paclitaxel in Participants With Stage IV Squamous Non-Small Cell Lung Cancer (NSCLC) [IMpower131]

Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 * Histologically or cytologically confirmed, treatment-naïve Stage IV squamous NSCLC * Previously obtained archival tumor tissue or tissue obtained from biopsy at screening * Measurable disease as defined by RECIST v1.1 * Adequate hematologic and end organ function Exclusion Criteria: * Active or untreated central nervous system (CNS) metastasis * Malignancies other than NSCLC within 5 years prior to randomization, with the exception of those with a negligible risk of metastasis or death treated with expected curative outcome * Pregnant or lactating women * History of autoimmune disease * History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening chest Computed Tomography (CT) scan, History of radiation pneumonitis in the radiation field (fibrosis) is permitted * Positive test for Human Immunodeficiency Virus (HIV) * Active hepatitis B or hepatitis C * Prior treatment with cluster of differentiation 137 (CD137) agonists or immune checkpoint blockade therapies, anti-programmed death-1 (anti-PD-1), and anti-PD-L1 therapeutic antibody * Severe infection within 4 weeks prior to randomization * Significant history of cardiovascular disease