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

base/utf_offset_string_conversions.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_UTF_OFFSET_STRING_CONVERSIONS_H_
 #define BASE_UTF_OFFSET_STRING_CONVERSIONS_H_
-#pragma once
 
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/string16.h"
 #include "base/string_piece.h"
 
 // Like the conversions in utf_string_conversions.h, but also takes one or more
 // offsets (|offset[s]_for_adjustment|) into the source strings, each offset
@@ skipping 63 matching lines @@
   void Add(const Adjustment& adjustment);
 
  private:
   void AdjustOffset(std::vector<size_t>::iterator offset);
 
   std::vector<size_t>* offsets_for_adjustment_;
   std::vector<Adjustment> adjustments_;
 };
 
 #endif  // BASE_UTF_OFFSET_STRING_CONVERSIONS_H_