Don't allow path traversal paths on the base file helpers

base/platform_file.cc

 // 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.
 
 #include "base/platform_file.h"
 
 namespace base {
 
 PlatformFileInfo::PlatformFileInfo()
     : size(0),
       is_directory(false),
       is_symbolic_link(false) {
 }
 
 PlatformFileInfo::~PlatformFileInfo() {}
 
+PlatformFile CreatePlatformFile(const FilePath& name,
+                                int flags,
+                                bool* created,
+                                PlatformFileError* error_code) {
+  if (name.ReferencesParent()) {
+    *error_code = PLATFORM_FILE_ERROR_ACCESS_DENIED;
+    return kInvalidPlatformFileValue;
+  }
+  return CreatePlatformFileAllowTraversal(name, flags, created, error_code);
+}
+
 }  // namespace base