Move dir_reader to base/files

base/dir_reader_fallback.h

-// Copyright (c) 2010 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_DIR_READER_FALLBACK_H_
-#define BASE_DIR_READER_FALLBACK_H_
-#pragma once
-
-namespace base {
-
-class DirReaderFallback {
- public:
-  // Open a directory. If |IsValid| is true, then |Next| can be called to start
-  // the iteration at the beginning of the directory.
-  explicit DirReaderFallback(const char* directory_path) { }
-  // After construction, IsValid returns true iff the directory was
-  // successfully opened.
-  bool IsValid() const { return false; }
-  // Move to the next entry returning false if the iteration is complete.
-  bool Next() { return false; }
-  // Return the name of the current directory entry.
-  const char* name() { return 0;}
-  // Return the file descriptor which is being used.
-  int fd() const { return -1; }
-  // Returns true if this is a no-op fallback class (for testing).
-  static bool IsFallback() { return true; }
-};
-
-}  // namespace base
-
-#endif  // BASE_DIR_READER_FALLBACK_H_