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

webkit/fileapi/quota_file_util.h

Index: webkit/fileapi/quota_file_util.h
diff --git a/webkit/fileapi/quota_file_util.h b/webkit/fileapi/quota_file_util.h
index efad64f1556e26a633bccce07e4d402d6931e789..76b02ea3a755d56cde17f23d960e3bf071f7a88e 100644
--- a/webkit/fileapi/quota_file_util.h
+++ b/webkit/fileapi/quota_file_util.h
@@ -6,27 +6,27 @@
 #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"
+#include "webkit/fileapi/fileapi_file_util.h"
+#include "webkit/fileapi/overlay_file_util.h"
 #pragma once
 
 namespace fileapi {
 
-class QuotaFileUtil : public FileSystemFileUtil {
+class QuotaFileUtil : public OverlayFileUtil {
  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());
+  // FileUtil* file_util = new QuotaFileUtil(new SomeFileUtil());
   //
-  // To instanciate an object whose underlying file_util is FileSystemFileUtil,
+  // To instanciate an object whose underlying file_util is FileUtil,
   // QuotaFileUtil::CreateDefault() can be used.
-  explicit QuotaFileUtil(FileSystemFileUtil* underlying_file_util);
+  explicit QuotaFileUtil(FileUtil* underlying_file_util);
   virtual ~QuotaFileUtil();
 
-  // Creates a QuotaFileUtil instance with an underlying FileSystemFileUtil
-  // instance.
+  // Creates a QuotaFileUtil instance with an underlying FileUtil instance.
   static QuotaFileUtil* CreateDefault();
 
   // TODO(dmikurube): Make this function variable by the constructor.
@@ -68,8 +68,6 @@ class QuotaFileUtil : public FileSystemFileUtil {
       int64 length) OVERRIDE;
 
  private:
-  scoped_ptr<FileSystemFileUtil> underlying_file_util_;
-
   // TODO(dmikurube): Make these constants variable by the constructor.
   //
   // These values are based on Obfuscation DB.  See crbug.com/86114 for the