Move FileEnumerator to its own file, do some refactoring.

base/test/test_file_util_posix.cc

 // 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.
 
 #include "base/test/test_file_util.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
 #include <string>
 
 #include "base/file_util.h"
+#include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 
-using base::MakeAbsoluteFilePath;
-
 namespace file_util {
 
 namespace {
 
 // Deny |permission| on the file |path|.
 bool DenyFilePermission(const base::FilePath& path, mode_t permission) {
   struct stat stat_buf;
   if (stat(path.value().c_str(), &stat_buf) != 0)
     return false;
   stat_buf.st_mode &= ~permission;
@@ skipping 77 matching lines @@
   DCHECK(info_ != NULL);
   DCHECK_NE(0u, length_);
 }
 
 PermissionRestorer::~PermissionRestorer() {
   if (!RestorePermissionInfo(path_, info_, length_))
     NOTREACHED();
 }
 
 }  // namespace file_util