[Refactor] to rename and re-layer the file_util stack layers.

webkit/fileapi/quota_file_util.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 WEBKIT_FILEAPI_QUOTA_FILE_UTIL_H_
 #define WEBKIT_FILEAPI_QUOTA_FILE_UTIL_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "webkit/fileapi/file_system_file_util.h"
 #include "webkit/fileapi/file_system_operation_context.h"
 #pragma once
 
 namespace fileapi {
 
 class QuotaFileUtil : public FileSystemFileUtil {
  public:
   static const int64 kNoLimit;
 
   // |underlying_file_util| is owned by the instance.  It will be deleted by
   // the owner instance.  For example, it can be instanciated as follows:
   // FileSystemFileUtil* file_util = new QuotaFileUtil(new SomeFileUtil());
   //
   // To instanciate an object whose underlying file_util is FileSystemFileUtil,
   // QuotaFileUtil::CreateDefault() can be used.
   explicit QuotaFileUtil(FileSystemFileUtil* underlying_file_util);
   virtual ~QuotaFileUtil();
 
-  // Creates a QuotaFileUtil instance with an underlying FileSystemFileUtil
+  // Creates a QuotaFileUtil instance with an underlying NativeFileUtil
   // instance.
   static QuotaFileUtil* CreateDefault();
 
+  virtual base::PlatformFileError Truncate(
+      FileSystemOperationContext* fs_context,
+      const FilePath& path,
+      int64 length) OVERRIDE;
   virtual base::PlatformFileError CopyOrMoveFile(
       FileSystemOperationContext* fs_context,
       const FilePath& src_file_path,
       const FilePath& dest_file_path,
       bool copy) OVERRIDE;
-
   virtual base::PlatformFileError DeleteFile(
       FileSystemOperationContext* fs_context,
       const FilePath& file_path) OVERRIDE;
 
-  virtual base::PlatformFileError Truncate(
-      FileSystemOperationContext* fs_context,
-      const FilePath& path,
-      int64 length) OVERRIDE;
-
  private:
-  scoped_ptr<FileSystemFileUtil> underlying_file_util_;
-
   DISALLOW_COPY_AND_ASSIGN(QuotaFileUtil);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_QUOTA_FILE_UTIL_H_