dbus: add support for passing file descriptors

dbus/file_descriptor.cc

Index: dbus/file_descriptor.cc
diff --git a/dbus/file_descriptor.cc b/dbus/file_descriptor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fc240f552c634524fb619e52095305fd054c5807
--- /dev/null
+++ b/dbus/file_descriptor.cc
@@ -0,0 +1,15 @@
+// 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/platform_file.h"
+#include "dbus/file_descriptor.h"
+
+namespace dbus {
+
+FileDescriptor::~FileDescriptor() {
+  if (owner_)
+    base::ClosePlatformFile(value_);
+}
+
+}  // namespace dbus