A Study of Atezolizumab Compared With Chemotherapy in Participants With Locally Advanced or Metastatic Urothelial Bladder Cancer [IMvigor211]

Inclusion Criteria:

* Histologically or cytologically documented locally advanced or metastatic UBC (including renal pelvis, ureters, urinary bladder, and urethra).
* Representative tumor specimens as specified by the protocol
* Disease progression during or following treatment with at least one platinum-containing regimen for inoperable, locally advanced or metastatic UBC or disease recurrence
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
* Life expectancy greater than or equal to (\>/=) 12 weeks
* Measurable disease, as defined by RECIST v1.1
* Adequate hematologic and end organ function
* For women of childbearing potential, agreement to refrain from heterosexual intercourse or use contraceptive methods that result in a failure rate of \< 1% per year during the treatment period and for at least 5 months after the last dose of atezolizumab, 3 months after the last dose of vinflunine and 6 months from the last dose of paclitaxel or docetaxel.
* For men, agreement to refrain from heterosexual intercourse or use contraceptive methods that result in a failure rate of \< 1% per year during the treatment period and for at least 3 months after the last dose of vinflunine and 6 months from the last dose of paclitaxel or docetaxel, and agreement to refrain from donating sperm

Exclusion Criteria:

* Any approved anti-cancer therapy within 3 weeks prior to initiation of study treatment
* Treatment with any other investigational agent or participation in another clinical trial with therapeutic intent within 28 days prior to enrollment
* Active or untreated central nervous system (CNS) metastases as determined by computed tomography (CT) or magnetic resonance imaging (MRI) evaluation during screening and prior radiographic assessments
* Leptomeningeal disease
* Malignancies other than UBC within 5 years prior to Cycle 1, Day 1, with the exception of those with a negligible risk of metastasis or death and treated with expected curative outcome, or localized prostate cancer treated with curative intent and absence of prostate-specific antigen (PSA) relapse or incidental prostate cancer
* Pregnant and lactating women
* Significant cardiovascular disease
* Severe infections within 4 weeks prior to randomization
* Major surgical procedure other than for diagnosis within 4 weeks prior to randomization
* 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
* Prior allogeneic stem cell or solid organ transplant
* History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening chest CT scan
* Positive test for human immunodeficiency virus (HIV) and/or active hepatitis B or hepatitis C or tuberculosis
* Administration of a live, attenuated vaccine within 4 weeks prior to randomization
* Prior treatment with cluster of differentiation 137 (CD137) agonists or immune checkpoint blockade therapies, including anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4), anti-programmed death-1 (anti-PD-1) or anti-programmed death-ligand 1 (anti-PD-L1) therapeutic antibodies