A Study to Detect V-Raf Murine Sarcoma Viral Oncogene Homolog B1 (BRAF) V600 Mutation on Cell-Free Deoxyribonucleic Acid (cfDNA) From Plasma in Participants With Advanced Melanoma

Participants will receive cobimetinib 60 mg tablets (three 20 mg tablet) orally OD for 21 consecutive days (Days 1 to 21), followed by a 7 day break (Days 22 to 28); in each 28-day cycle of treatment phase until disease progression, consent withdrawal, or the development of unacceptable toxicity.

Participants will receive vemurafenib 960 mg tablets (four 240 mg tablet) orally BID from Day 1 to Day 28 of each 28-day cycle of the treatment phase until disease progression, consent withdrawal, or the development of unacceptable toxicity.