anchor.diff:  
     gypFlagsUseSystemLibs = {
       use_system_bzip2 = true;
  -    use_system_ffmpeg = false; # FIXME: libavformat...
       use_system_flac = true;
       use_system_harfbuzz = false; # TODO
       use_system_icu = false; # FIXME: wrong version!
  
positive.code:     useOpenSSL = true;
      enableGnomeSupport = false;
      gnomeKeyringSupport = false;
      useProprietaryCodecs = false;
      enableCUPS = false;
    };
  
  
negative.code:     use_openssl = config.useOpenSSL;
      selinux = config.useSELinux;
      use_cups = config.enableCUPS;
    } // stdenv.lib.optionalAttrs config.useProprietaryCodecs {
      # enable support for the H.264 codec
      proprietary_codecs = true;
      ffmpeg_branding = "Chrome";
    } // stdenv.lib.optionalAttrs (stdenv.system == "x86_64-linux") {
      target_arch = "x64";
    } // stdenv.lib.optionalAttrs (stdenv.system == "i686-linux") {
  