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

base/test/perf_test_suite.h

 // Copyright (c) 2011 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_TEST_PERF_TEST_SUITE_H_
 #define BASE_TEST_PERF_TEST_SUITE_H_
-#pragma once
 
 #include "base/test/test_suite.h"
 
 namespace base {
 
 class PerfTestSuite : public TestSuite {
  public:
   PerfTestSuite(int argc, char** argv);
 
   virtual void Initialize() OVERRIDE;
   virtual void Shutdown() OVERRIDE;
 };
 
 }  // namespace base
 
 #endif  // BASE_TEST_PERF_TEST_SUITE_H_