Replace OwnPtr with WTF::Optional for optional recorders.

Source/wtf/Utility.h

+// Copyright 2015 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 Utility_h
+#define Utility_h
+
+#include "wtf/TypeTraits.h"
+
+namespace WTF {
+
+// TODO(jbroman): When a C++11 standard library is available, replace this with
+// std::forward from <utility>.
+
+template <typename T>
+T&& forward(typename RemoveReference<T>::Type& t) { return static_cast<T&&>(t); }
+
+template <typename T>
+T&& forward(typename RemoveReference<T>::Type&& t) { return static_cast<T&&>(t); }
+
+} // namespace WTF
+
+#endif // Utility_h