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Contributor Setup

This chapter is for contributors who modify CBF crates, bridge code, or Chromium-fork patches.

1. Prerequisites

You need the following tools installed and configured:

  • Stable Rust toolchain
  • Git
  • Python 3
  • depot_tools
  • Chromium build dependencies for your OS
  • Chromium source code

For downloading Chromium source code and depot_tools and setting up the Chromium build environment, follow the official guide: https://chromium.googlesource.com/chromium/src/+/HEAD/docs/get_the_code.md

You should place Chromium source tree at chromium/src relative to the repository root. This allows build scripts to locate bridge artifacts without additional configuration. It is also recommended to place depot_tools at ./depot_tools relative to the repository root so helper commands can discover it consistently.

2. Build Chromium targets

Before building, generate GN build files (this creates chromium/src/out/Default/args.gn):

cd chromium/src
gn gen out/Default

Optionally, you can tune out/Default/args.gn for CBF development. Example:

# Build release-like binaries for faster runtime and smaller output.
is_debug = false

# Keep DCHECK-enabled behavior even in non-debug builds.
# This is important for CBF development since CBF and Chromium often rely
# on DCHECKs to validate invariants and catch issues early.
dcheck_always_on = true

# Use component build for faster incremental link/build cycles.
is_component_build = true

# Enable ccache via wrapper to speed up repeated C/C++ compilation.
cc_wrapper = "env CCACHE_SLOPPINESS=time_macros ccache"

# Reduce overall symbol volume.
symbol_level = 1

# CBF usually does not modify Blink/V8 internals, so strip more symbols there.
blink_symbol_level = 0
v8_symbol_level = 0

Then build relevant targets with autoninja from chromium/src:

autoninja -C out/Default chrome
autoninja -C out/Default cbf_bridge

This builds the main Chromium target and the CBF bridge library, which is required for cbf-chrome-sys to link successfully.

Release packaging uses a separate chromium/src/out/Release directory and a different args.gn policy. See Release Process for the release-specific flow.

Warning

Chromium builds can take several hours or longer, and CPU usage may stay high during the entire build, which can keep sustained load on your machine. Because builds are long-running, you can mitigate sleep-related build interruption by using tools such as caffeinate of macOS.

3. Configure bridge linkage

cbf-chrome-sys and cbf-chrome needs bridge artifacts from CBF_BRIDGE_LIB_DIR:

export CBF_BRIDGE_LIB_DIR="/path/to/chromium/src/out/Default"

Then run focused checks:

cargo check -p cbf
cargo check -p cbf-chrome
cargo check -p cbf-chrome-sys
cargo test -p cbf
cargo test -p cbf-chrome
cargo test -p cbf-chrome-sys

4. Contributor validation checklist

  • Rust crates compile and tests pass for touched areas.
  • Rust code changes are formatted with cargo fmt.
  • Rust code follows lint rules with cargo clippy.
  • cbf_bridge builds against current Chromium revision.
  • Run Chromium-side tests as needed based on the impact scope of your changes (see Chromium Fork Workflow for how to run them).

5. Where to continue