Chrome Blink and CC Finch Experiment Guide

The source material is a comprehensive guide detailing the process for Google Chrome engineers to launch an A/B field trial (experiment) for changes made to the rendering engine (Blink) or the compositor (cc) using Chrome’s internal variations system, Finch. It specifies the technical steps involved in creating feature flags (like base::Feature or RuntimeEnabledFeatures), ensuring the new code is disabled by default, and wiring these flags to the Finch infrastructure for remote control. The guide also covers the necessary steps for local testing via command-line flags, integrating UMA metrics for experiment analysis, obtaining required OWNERS reviews (including Blink API owners), and executing a phased rollout plan across Canary, Beta, and Stable channels, emphasizing the importance of monitoring guardrail metrics and having a kill-switch capability.