Study of Pembrolizumab (MK-3475) Versus Platinum-Based Chemotherapy for Participants With Programmed Cell Death-Ligand 1 (PD-L1)-Positive Advanced or Metastatic Non-Small Cell Lung Cancer (MK-3475-042/KEYNOTE-042)

Inclusion criteria: * Histologically- or cytologically-confirmed diagnosis of advanced or metastatic NSCLC * PD-L1 positive tumor * Measureable disease based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 * Life expectancy of at least 3 months * No prior systemic chemotherapy for the treatment of the participant's advanced or metastatic disease (treatment with chemotherapy and/or radiation as part of neoadjuvant/adjuvant therapy is allowed as long as completed at least 6 months prior to diagnosis of advanced or metastatic disease) * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Adequate organ function * No prior malignancy, with the exception of basal cell carcinoma of the skin, superficial bladder cancer, squamous cell carcinoma of the skin, or in situ cancer, or has undergone potentially curative therapy with no evidence of that disease recurrence for 5 years since initiation of that therapy * Submission of formalin-fixed diagnostic tumor tissue (in the case of participants having received adjuvant systemic therapy, the tissue should be taken after completion of this therapy) * Female participants of childbearing potential must have a negative urine or serum pregnancy test and must be willing to use two adequate barrier methods of contraception or a barrier method plus a hormonal method starting with the screening visit through 120 days after the last dose of pembrolizumab or 180 days after the last dose of chemotherapeutic agents u…