It appears that the official chrome webstore extension by Rob W is outdated.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

mkdirp.sync(BUILD_DIR + "tmp/");
  const bytes = require("crypto").randomBytes(6).toString("hex");
  const filePath = BUILD_DIR + "tmp/" + prefix + bytes + suffix;
  fs.writeFileSync(filePath, "");
  return filePath;
}
function createTestSource(testsName, { bot = false, xfaOnly = false } = {}) {
  const source = stream.Readable({ objectMode: true });
  source._read = function () {
    console.log();
    console.log("### Running " + testsName + " tests");
    const PDF_TEST = process.env.PDF_TEST || "test_manifest.json";
    let forceNoChrome = false;
    const args = ["test.js"];
    switch (testsName) {
      case "browser":
        if (!bot) {
          args.push("--reftest");
        } else {
          const os = process.env.OS;
          if (/windows/i.test(os)) {
            
            
            forceNoChrome = true;
          }
        }
        if (xfaOnly) {
          args.push("--xfaOnly");
        }