It appears that the official chrome webstore extension by Rob W is outdated.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

console.log();
  console.log("### Creating baseline environment");
  const baselineCommit = process.env.BASELINE;
  if (!baselineCommit) {
    done(new Error("Missing baseline commit. Specify the BASELINE variable."));
    return;
  }
  let initializeCommand = "git fetch origin";
  if (!checkDir(BASELINE_DIR)) {
    mkdirp.sync(BASELINE_DIR);
    initializeCommand = "git clone ../../ .";
  }
  const workingDirectory = path.resolve(process.cwd(), BASELINE_DIR);
  exec(initializeCommand, { cwd: workingDirectory }, function (error) {
    if (error) {
      done(new Error("Baseline clone/fetch failed."));
      return;
    }
    exec(
      "git checkout " + baselineCommit,
      { cwd: workingDirectory },
      function (error2) {
        if (error2) {
          done(new Error("Baseline commit checkout failed."));
          return;
        }
        console.log('Baseline commit "' + baselineCommit + '" checked out.');
        done();