It appears that the official chrome webstore extension by Rob W is outdated. It was last updated in 2019. 

},
    content
  );
  return (
    licenseHeader +
    "\n" +
    GLOBALS +
    "\n" +
    MODIFICATION_WARNING +
    "\n" +
    content +
    "\n"
  );
}
gulp.task(
  "mozcentral",
  gulp.series(
    createBuildNumber,
    function scriptingMozcentral() {
      const defines = builder.merge(DEFINES, { MOZCENTRAL: true });
      return buildDefaultPreferences(defines, "mozcentral/");
    },
    function createMozcentral() {
      console.log();
      console.log("### Building mozilla-central extension");
      const defines = builder.merge(DEFINES, { MOZCENTRAL: true });
      const MOZCENTRAL_DIR = BUILD_DIR + "mozcentral/",
        MOZCENTRAL_EXTENSION_DIR = MOZCENTRAL_DIR + "browser/extensions/pdfjs/",
        MOZCENTRAL_CONTENT_DIR = MOZCENTRAL_EXTENSION_DIR + "content/",
        MOZCENTRAL_L10N_DIR =