Update from https://crrev.com/305340

sandbox/linux/tests/test_utils.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_TESTS_TEST_UTILS_H_
 #define SANDBOX_LINUX_TESTS_TEST_UTILS_H_
 
+#include <sys/types.h>
+
 #include "base/basictypes.h"
 
 namespace sandbox {
 
 // This class provide small helpers to help writing tests.
 class TestUtils {
  public:
   static bool CurrentProcessHasChildren();
+  // |pid| is the return value of a fork()-like call. This
+  // makes sure that if fork() succeeded the child exits
+  // and the parent waits for it.
+  static void HandlePostForkReturn(pid_t pid);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(TestUtils);
 };
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_TESTS_TEST_UTILS_H_