A Study of Atezolizumab (Tecentriq) to Investigate Long-term Safety and Efficacy in Previously-treated Participants With Locally Advanced or Metastatic Non-small Cell Lung Cancer (NSCLC)

Inclusion Criteria:

* Histologically or cytologically documented Stage IIIb or Stage IV NSCLC that has progressed following standard systemic chemotherapy (including if given in combination with anti-PD-1 therapy, after anti-PD-1 as monotherapy, or after TKI therapy). Participants with a previously detected sensitizing epidermal growth factor receptor (EGFR) mutation or echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (ALK) fusion oncogene must have received targeted therapy (TKI) followed by at least one line of standard systemic chemotherapy prior to receiving atezolizumab. Overall, participants should not have received more than two lines of standard systemic chemotherapy. Participants who have discontinued first-line or second-line therapy due to intolerance are also eligible
* The last dose of prior systemic anticancer therapy or targeted therapy must have been administered more than or equal to (≥) 21 days prior to randomization.
* The last dose of prior anti-PD-1 therapy must have been administered. Nivolumab must have been discontinued \>= 14 days and pembrolizumab \>= 21 days prior to study treatment initiation, providing that these treatments were not administered in a clinical trial setting.
* Measurable disease, as defined by Response Evaluation Criteria for Solid Tumors, Version 1.1 (RECIST v1.1)
* Participants with asymptomatic central nervous system (CNS) metastases (treated or untreated), as determined by computed tomography (CT) or magnetic resonance imaging evaluation during screening and prior radiographic evaluation, are eligible
* Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2
* Life expectancy ≥ 12 weeks
* Adequate hematologic and end-organ function
* For women of childbearing potential: 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 5 months after the last dose of atezolizumab
* Participants must have recovered (i.e., improvement to Grade 1 or better) from all acute toxicities from previous therapy, excluding alopecia and toxicities related to prior anti-PD-1-therapy

Exclusion Criteria:

* Symptomatic CNS metastases
* Spinal cord compression not definitively treated with surgery and/or radiation or previously diagnosed and treated spinal cord compression without evidence that disease has been clinically stable for ≥ 2 weeks prior to study treatment initiation
* Leptomeningeal disease
* Uncontrolled pericardial effusion or ascites requiring recurrent drainage procedures
* Pregnant or lactating, or intending to become pregnant during the study
* Evidence of significant uncontrolled concomitant disease that could affect compliance with the protocol, including significant liver disease (such as cirrhosis, uncontrolled major seizure disorder, or superior vena cava syndrome)
* Significant cardiovascular disease, such as New York Heart Association cardiac disease ≥ Class III, myocardial infarction within 3 months, unstable arrhythmias, or unstable angina
* Significant renal disorder requiring dialysis or indication for renal transplant
* Treatment with any other investigational agent or participation in another clinical trial with therapeutic intent within 28 days prior to study treatment initiation
* Major surgical procedure within 4 weeks prior to study treatment initiation or anticipation of need for a major surgical procedure during the course of the study other than for diagnosis
* Inability to understand the local language(s) for which the EORTC QLQ-LC13 and EQ-5D-5L questionnaires are available
* History of severe allergic, anaphylactic, or other hypersensitivity reactions to chimeric or humanized antibodies or fusion proteins
* Known hypersensitivity or allergy to biopharmaceuticals produced in Chinese hamster ovary cells or any component of the atezolizumab formulation
* History of autoimmune disease are allowed if controlled and on stable treatment (i.e., same treatment, same dose) for the last 12 weeks
* Prior allogeneic stem cell or solid organ transplantation
* History of idiopathic pulmonary fibrosis, including pneumonitis, drug-induced pneumonitis, organizing pneumonia (i.e., bronchiolitis obliterans, cryptogenic organizing pneumonia), or evidence of active pneumonitis on screening chest CT scan
* Active tuberculosis
* Administration of a live, attenuated vaccine within 4 weeks prior to study treatment initiation
* Prior treatment with cluster of differentiation 137 (CD137) agonists or immune checkpoint blockade therapies other than anti-PD-1 therapy, including anti-programmed death-ligand 1 therapeutic antibodies
* Treatment with systemic immunostimulatory agents (including, but not limited to, interferons or interleukin-2) within 4 weeks or five half-lives of the drug, whichever is longer, prior to initiation of study treatment
* Specifically for participants without autoimmune disease: treatment with systemic corticosteroids or other systemic immunosuppressive medications (including but not limited to prednisone, dexamethasone, cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor agents) within 2 weeks prior to study treatment initiation, or anticipated requirement for systemic immunosuppressive medications during the trial. For participants with CNS metastases, use of prednisone at a stable dose (or dose equivalent) of \<= 20 mg/day is acceptable.