Introduce FileSystemFileUtil and -Proxy to decorate base::file_util in webkit/fileapi.

webkit/fileapi/file_system_operation_context.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_FILE_SYSTEM_OPERATION_CONTEXT_H_
+#define WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_CONTEXT_H_
+
+#include "webkit/fileapi/file_system_file_util.h"
+
+namespace fileapi {
+
+class FileSystemOperationContext {
+ public:
+  FileSystemOperationContext(FileSystemFileUtil* file_system_file_util)
+      : file_system_file_util_(file_system_file_util) {
+  }
+
+  FileSystemFileUtil* file_system_file_util() const {
+    return file_system_file_util_;
+  }
+
+ private:
+  // This file_system_file_util_ is not "owned" by FileSystemOperationContext.
+  // It is supposed to be a pointer to a singleton.
+  FileSystemFileUtil* file_system_file_util_;
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_CONTEXT_H_