Steps to build Skia on MacOS

build.sh

# brew install ninja

mkdir $HOME/deps
cd $HOME/deps
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
git clone https://github.com/google/skia.git
export PATH="${PWD}/depot_tools:${PATH}"
cd skia
python tools/git-sync-deps

# static
# bin/gn gen out/release --args="is_official_build=true skia_use_system_expat=false skia_use_system_icu=false skia_use_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_libwebp=false extra_cflags_cc=[\"-frtti\"]"
bin/gn gen out/release-static --args="is_official_build=true skia_use_libjpeg_turbo_decode=false skia_use_libjpeg_turbo_encode=false skia_use_system_expat=false skia_use_system_icu=false skia_use_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_libwebp=false extra_cflags_cc=[\"-frtti\"] target_cpu=\"arm64\""

# dynamic
# bin/gn gen out/release --args="is_official_build=true is_component_build=true skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false extra_cflags_cc=[\"-frtti\"]"

ninja -C out/release-static skia