openscreen is built in Chromium with some build differences. The files that are built in openscreen are determined by the following build variables.
build_with_chromium: true when building as part of a Chromium checkout, false otherwise. Defined //build_overrides/build.gni in Chromium.use_mdns_responder: true by default, false when build_with_chromium is true. Controls whether the default mDNSResponder mDNS implementation is used. Set by openscreen/src/build/config/services.gni.use_chromium_quic: true by default, false when build_with_chromium is true. Controls whether the Chromium-derived QUIC implementation in openscreen is used. Set by openscreen/src/build/config/services.gni.