Revert of base: Fix/add header #ifndef guards.

base/mac/libdispatch_task_runner.h

 // Copyright (c) 2012 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 BASE_MAC_LIBDISPATCH_TASK_RUNNER_H_
-#define BASE_MAC_LIBDISPATCH_TASK_RUNNER_H_
+#ifndef BASE_MAC_LIBDISPATCH_SEQUENCED_TASK_RUNNER_H_
+#define BASE_MAC_LIBDISPATCH_SEQUENCED_TASK_RUNNER_H_
 
 #include <dispatch/dispatch.h>
 
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/waitable_event.h"
 
 namespace base {
 namespace mac {
 
 // This is an implementation of the TaskRunner interface that runs closures on
@@ skipping 53 matching lines @@
 
   dispatch_queue_t queue_;
 
   // The event on which Shutdown waits until Finalizer runs.
   base::WaitableEvent queue_finalized_;
 };
 
 }  // namespace mac
 }  // namespace base
 
-#endif  // BASE_MAC_LIBDISPATCH_TASK_RUNNER_H_
+#endif  // BASE_MAC_LIBDISPATCH_SEQUENCED_TASK_RUNNER_H_