Move sequenced_task_runner to base/task

base/task/sequenced_task_runner_helpers.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_SEQUENCED_TASK_RUNNER_HELPERS_H_
-#define BASE_SEQUENCED_TASK_RUNNER_HELPERS_H_
+#ifndef BASE_TASK_SEQUENCED_TASK_RUNNER_HELPERS_H_
+#define BASE_TASK_SEQUENCED_TASK_RUNNER_HELPERS_H_
 
 #include "base/basictypes.h"
 
 // TODO(akalin): Investigate whether it's possible to just have
 // SequencedTaskRunner use these helpers (instead of MessageLoop).
 // Then we can just move these to sequenced_task_runner.h.
 
 namespace tracked_objects {
 class Location;
 }
@@ skipping 85 matching lines @@
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ReleaseHelperInternal);
 };
 
 }  // namespace subtle
 
 }  // namespace base
 
-#endif  // BASE_SEQUENCED_TASK_RUNNER_HELPERS_H_
+#endif  // BASE_TASK_SEQUENCED_TASK_RUNNER_HELPERS_H_