Chrome Blink and CC Finch Experiment Guide
Blink28629 Loka 2025

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.


Jaksot(397)

gpu::SkiaOutputSurfaceImplOnGpu / gpu::CommandBuffer

gpu::SkiaOutputSurfaceImplOnGpu / gpu::CommandBuffer

Bridges Skia’s recorded commands to the GPU command buffer; submits and SwapBuffers to present. (Backend: GL/Vulkan/Metal via GPU process.)

23 Syys 202532min

viz::SkiaRenderer

viz::SkiaRenderer

Renderer that turns quads into Skia operations (recording DDLs / drawing to the output surface).

23 Syys 202552min

viz::Display

viz::Display

The display compositor that walks the aggregated render passes and issues draw commands for the final output.

23 Syys 202538min

cc::LayerTreeHostImpl (Input Handler & Scroll Logic)

cc::LayerTreeHostImpl (Input Handler & Scroll Logic)

Scroll processing and overscroll detection in the compositor. The LayerTreeHostImpl in cc implements the compositor-thread InputHandler that processes gesture scroll updates and flings. It manages the...

23 Syys 202527min

blink::EventHandler (Blink core input handling)

blink::EventHandler (Blink core input handling)

Scroll chain builder and overscroll chaining logic. Blink’s EventHandler is responsible for building the scroll chain (the sequence of nested scrollable ancestors) when the user scrolls an element . I...

23 Syys 202526min

blink::ElasticOverscrollController

blink::ElasticOverscrollController

Overscroll orchestration and animation. This Blink-side controller manages the rubber-banding (elastic stretch and rebound) effect when a scrollable area is overscrolled. It observes gesture scroll ev...

23 Syys 202526min

viz::Surface / SurfaceAggregator

viz::Surface / SurfaceAggregator

Receives frames from one or more surfaces (main page and OOPIFs), aggregates them into a single display frame.

23 Syys 202535min

viz::CompositorFrameSink (client side)

viz::CompositorFrameSink (client side)

The submission interface used by cc to hand the frame to viz.

23 Syys 202531min