# Chromium
Let's assume we're trying to build chromium with `sancov`. Although this is possible purely with `gn` arguments, I'll demonstrate this with system toolchain.

First, create a file at `out/sancov/args.gn`. The contents of the file should be as follows:
```
custom_toolchain="//build/toolchain/linux/unbundle:default"
host_toolchain="//build/toolchain/linux/unbundle:default"
is_clang = true
clang_use_chrome_plugins = false
```

Second, execute the following commands.
```bash
export LLVM_BIN_DIR="/usr/local/bin"
export CC="$LLVM_BIN_DIR/clang"
export CXX="$LLVM_BIN_DIR/clang++"
export AR="$LLVM_BIN_DIR/llvm-ar"
export SOLINK="$LLVM_BIN_DIR/lld"
export NM="$LLVM_BIN_DIR/llvm-nm"
export LDFLAGS="-fsanitize-coverage=trace-pc-guard"
gn gen out/sancov 
autoninja -C out/sancov chrome
```