A Study Evaluating Atezolizumab, With or Without Bevacizumab, in Participants With Unresectable Hepatocellular Carcinoma and Child-pugh B7 and B8 Cirrhosis

General Inclusion Criteria: * Locally advanced or metastatic and/or unresectable HCC with diagnosis confirmed by histology/cytology or clinically by American Association for the Study of Liver Diseases (AASLD) criteria in cirrhotic participants * Disease that is not amenable to curative surgical and/or locoregional therapies * No prior systemic treatment (including systemic investigational agents) for locally advanced or metastatic and/or unresectable HCC * Measurable disease (at least one untreated target lesion) according to Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1) * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 within 7 days prior to initiation of study treatment * Child-pugh B7 or B8 cirrhosis at screening and within 7 days prior to study treatment * Adequate hematologic and end-organ function * Life expectancy of at least 12 weeks * Female participants of childbearing potential must be willing to avoid pregnancy and egg donation * Absolute neutrophil count ≥1.0 x 10\^9 per liter (/L) (≥1000 per microliter \[/μL\]) without granulocyte colony-stimulating factor support * Platelet count ≥ 50 × 109/L (50,000/μL) without transfusion * Hemoglobin ≥ 80 grams per liter (g/L) (8 grams per deciliter \[g/dL\]) aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 5 × upper limit of normal (ULN) * Serum bilirubin ≤ 3 × ULN * Creatinine clearance ≥ 50 milliliters per minute (mL/min) (calculated using the Cockcroft-…