Study of Atezolizumab in Combination With Cobimetinib in Participants With Locally Advanced or Metastatic Solid Tumors

Inclusion Criteria: * Solid tumor that is metastatic, locally advanced or recurrent * 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 v 1.1 * Adequate hematologic and end organ function * Use of highly effective contraception * Histological tumor tissue specimen * Participants enrolling in the indication-specific expansion cohorts in Stage 2 must consent to tumor biopsies and must have one of the following types of cancer: * Metatastic colorectal cancer * Non-small cell lung cancer * Melanoma Exclusion Criteria: Cancer-Specific Exclusion Criteria: * Any approved anti-cancer therapy, including chemotherapy, or hormonal 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 * Known active or untreated central nervous system (CNS) metastases * Leptomeningeal disease * Uncontrolled tumor-related pain or uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent (once monthly or more frequently) drainage procedures * Uncontrolled hypercalcemia or symptomatic hypercalcemia requiring continued use of bisphosphonate therapy or denosumab General Medical Exclusion Criteria: * Pregnant and lactating women * History of severe allergic, anaphylactic, or other hypersensitivity reactions to chimeric or humanized antibodies or fusion proteins * Known hypersensitivity to biopharmaceuticals produced in Chinese hamster ovary cell or any component of the atezolizumab formulation * History of autoimmune disease * Participants with prior allogeneic stem cell or solid organ transplantation * Positive test for human immunodeficiency virus (HIV) * Participants with active hepatitis B, hepatitis C, or tuberculosis * Severe infections within 4 weeks prior to Cycle 1 Day 1 * Signs or symptoms of infection within 2 weeks prior to Cycle 1 Day 1 * Received therapeutic oral or IV antibiotics within 2 weeks prior to Cycle 1 Day 1 * Significant cardiovascular disease * Major surgical procedure other than for diagnosis within 28 days prior to Cycle 1 Day 1 or anticipation of need for a major surgical procedure during the course of the study * Administration of a live, attenuated vaccine within 4 weeks before Cycle 1 Day 1 Exclusion Criteria Unique to Cobimetinib: * History of prior significant toxicity from another mitogen-activated protein kinase (MEK) pathway inhibitor requiring discontinuation of treatment * Allergy or hypersensitivity to components of the cobimetinib formulations * History of congenital long QT syndrome or corrected QT interval (QTc) greater than (\>) 450 milliseconds at screening * Left ventricular ejection fraction (LVEF) below institutional lower limit of normal (LLN) or below 50%, whichever is lower, as determined by echocardiogram or Multi Gated Acquisition Scan (MUGA) scan * History of or evidence of retinal pathology on ophthalmologic examination that is considered a risk factor for neurosensory retinal detachment, central serous chorioretinopathy (CSCR), retinal vein occlusion (RVO), or neovascular macular degeneration * History of malabsorption syndrome or other condition that would interfere with enteral absorption Exclusion Criteria Related to Medications: * Prior treatment with clusters of differentiation (CD) 137 agonists or immune checkpoint blockade therapies, systemic immunostimulatory agents, or systemic immunosuppressive medications