Remove #pragma once from chrome/browser/extensions

chrome/browser/extensions/api/file_system/file_system_api.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 CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_
-#pragma once
 
 #include "chrome/browser/extensions/extension_function.h"
 #include "chrome/browser/ui/select_file_dialog.h"
 
 namespace extensions {
 
 class FileSystemGetDisplayPathFunction : public SyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION_NAME("fileSystem.getDisplayPath");
 
@@ skipping 57 matching lines @@
 
  private:
   // FileSelected and FileSelectionCanceled are called by the file picker.
   void FileSelected(const FilePath& path, EntryType entry_type);
   void FileSelectionCanceled();
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_