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

base/path_service.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_PATH_SERVICE_H_
 #define BASE_PATH_SERVICE_H_
-#pragma once
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/base_paths.h"
 #include "build/build_config.h"
 
 class FilePath;
 
 // The path service is a global table mapping keys to file system paths.  It is
@@ skipping 44 matching lines @@
   static void RegisterProvider(ProviderFunc provider,
                                int key_start,
                                int key_end);
  private:
   static bool GetFromCache(int key, FilePath* path);
   static bool GetFromOverrides(int key, FilePath* path);
   static void AddToCache(int key, const FilePath& path);
 };
 
 #endif  // BASE_PATH_SERVICE_H_