Remove #pragma once. Just from base/ for now.

base/test/sequenced_task_runner_test_template.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.
 
 // This class defines tests that implementations of SequencedTaskRunner should
 // pass in order to be conformant. See task_runner_test_template.h for a
 // description of how to use the constructs in this file; these work the same.
 
 #ifndef BASE_SEQUENCED_TASK_RUNNER_TEST_TEMPLATE_H_
 #define BASE_SEQUENCED_TASK_RUNNER_TEST_TEMPLATE_H_
-#pragma once
 
 #include <cstddef>
 #include <iosfwd>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner.h"
@@ skipping 212 matching lines @@
 
 REGISTER_TYPED_TEST_CASE_P(SequencedTaskRunnerTest,
                            SequentialNonNestable,
                            SequentialNestable,
                            SequentialDelayedNonNestable,
                            NonNestablePostFromNonNestableTask);
 
 }  // namespace base
 
 #endif  // BASE_TASK_RUNNER_TEST_TEMPLATE_H_