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