anchor.diff:    /// Restore Chrome user information from a per-project cache into Chrome's
     /// user data directory.
     void _restoreUserSessionInformation(Directory cacheDir, Directory userDataDir) {
  -    final Directory sourceChromeDefault = _fileSystem.directory(_fileSystem.path.join(cacheDir.path ?? '', _chromeDefaultPath));
  +    final Directory sourceChromeDefault = _fileSystem.directory(_fileSystem.path.join(cacheDir.path, _chromeDefaultPath));
       final Directory targetChromeDefault = _fileSystem.directory(_fileSystem.path.join(userDataDir.path, _chromeDefaultPath));
       try {
         if (sourceChromeDefault.existsSync()) {
  
positive.code:   /// [skipCheck] does not attempt to make a devtools connection before returning.
    Future<Chromium> launch(String url, {
      bool headless = false,
      int debugPort,
      bool skipCheck = false,
      Directory cacheDir,
    }) async {
      if (currentCompleter.isCompleted) {
        throwToolExit('Only one instance of chrome can be started.');
  
negative.code:       url,
      ];
  
      final Process? process = await _spawnChromiumProcess(args);
  
      // When the process exits, copy the user settings back to the provided data-dir.
      if (process != null && cacheDir != null) {
        unawaited(process.exitCode.whenComplete(() {
          _cacheUserSessionInformation(userDataDir, cacheDir);
        }));
  