@@ -145,6 +145,10 @@ public class TemporaryFilesystem {
   }
 
   public boolean deleteBaseDir() {
-    return baseDir.delete();
+    boolean wasDeleted = baseDir.delete();
+    if (wasDeleted) {
+      Runtime.getRuntime().removeShutdownHook(shutdownHook);
+    }
+    return wasDeleted;
   }
 }
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package org.openqa.selenium.io;

import org.openqa.selenium.WebDriverException;

import java.io.File;
import java.io.IOException;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * A wrapper around temporary filesystem behaviour.
 */
public class TemporaryFilesystem {

  private final Set<File> temporaryFiles = new CopyOnWriteArraySet<File>();
  private final File baseDir;
  private final Thread shutdownHook = new Thread() {  // Thread safety reviewed
    @Override
    public void run() {
      deleteTemporaryFiles();
    }
  };

  private static File sysTemp = new File(System.getProperty("java.io.tmpdir"));
  private static TemporaryFilesystem instance = new TemporaryFilesystem(sysTemp);

  public static TemporaryFilesystem getDefaultTmpFS() {
    return instance;
  }

  public static void setTemporaryDirectory(File directory) {
    synchronized (TemporaryFilesystem.class) {
      instance = new TemporaryFilesystem(directory);
    }
  }

  public static TemporaryFilesystem getTmpFsBasedOn(File directory) {
    return new TemporaryFilesystem(directory);
  }


  private TemporaryFilesystem(File baseDir) {
    this.baseDir = baseDir;

    Runtime.getRuntime().addShutdownHook(shutdownHook);

    if (!baseDir.exists()) {
      throw new WebDriverException("Unable to find tmp dir: " + baseDir.getAbsolutePath());
    }
    if (!baseDir.canWrite()) {
      throw new WebDriverException("Unable to write to tmp dir: " + baseDir.getAbsolutePath());
    }

  }

  /**
   * Create a temporary directory, and track it for deletion.
   *
   * @param prefix the prefix to use when creating the temporary directory
   * @param suffix the suffix to use when creating the temporary directory
   * @return the temporary directory to create
   */
  public File createTempDir(String prefix, String suffix) {
    try {
      // Create a tempfile, and delete it.
      File file = File.createTempFile(prefix, suffix, baseDir);
      file.delete();

      // Create it as a directory.
      File dir = new File(file.getAbsolutePath());
      if (!dir.mkdirs()) {
        throw new WebDriverException("Cannot create profile directory at " + dir.getAbsolutePath());
      }

      // Create the directory and mark it writable.
      FileHandler.createDir(dir);

      temporaryFiles.add(dir);
      return dir;
    } catch (IOException e) {
      throw new WebDriverException(
          "Unable to create temporary file at " + baseDir.getAbsolutePath());
    }
  }

  /**
   * Delete a temporary directory that we were responsible for creating.
   *
   * @param file the file to delete
   * @throws WebDriverException if interrupted
   */
  public void deleteTempDir(File file) {
    if (!shouldReap()) {
      return;
    }

    // If the tempfile can be removed, delete it. If not, it wasn't created by us.
    if (temporaryFiles.remove(file)) {
      FileHandler.delete(file);
    }
  }

  /**
   * Perform the operation that a shutdown hook would have.
   */
  public void deleteTemporaryFiles() {
    if (!shouldReap()) {
      return;
    }

    for (File file : temporaryFiles) {
      try {
        FileHandler.delete(file);
      } catch (WebDriverException e) {
        // ignore; an interrupt will already have been logged.
      }
    }
  }

  /**
   * Returns true if we should be reaping profiles. Used to control tempfile deletion.
   *
   * @return true if reaping is enabled.
   */
  boolean shouldReap() {
    String reap = System.getProperty("webdriver.reap_profile", "true");
    return Boolean.valueOf(reap);
  }

  public boolean deleteBaseDir() {
    return baseDir.delete();
  }
}

I don't think we need to necessarily check if that returned true or not, we should just remove the shutdown hook. Since nothing would check or do anything with this flag anyways.