Replace OwnPtr with WTF::Optional for optional recorders.

Source/wtf/OptionalTest.cpp

Index: Source/wtf/OptionalTest.cpp
diff --git a/Source/wtf/OptionalTest.cpp b/Source/wtf/OptionalTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7974637fce57ece4ce8a8c4b62cbc0fb18e8ad88
--- /dev/null
+++ b/Source/wtf/OptionalTest.cpp
@@ -0,0 +1,63 @@
+// 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.
+
+#include "config.h"
+#include "wtf/Optional.h"
+
+#include <gtest/gtest.h>
+
+namespace WTF {
+namespace {
+
+struct IntBox {
+    IntBox(int n) : number(n) { }
+    int number;
+};
+
+class DestructionNotifier {
+public:
+    DestructionNotifier(bool& flag) : m_flag(flag) { }
+    ~DestructionNotifier() { m_flag = true; }
+private:
+    bool& m_flag;
+};
+
+TEST(OptionalTest, BooleanTest)
+{
+    Optional<int> optional;
+    EXPECT_FALSE(optional);
+    optional.emplace(0);
+    EXPECT_TRUE(optional);
+}
+
+TEST(OptionalTest, Dereference)
+{
+    Optional<int> optional;
+    optional.emplace(1);
+    EXPECT_EQ(1, *optional);
+
+    Optional<IntBox> optionalIntbox;
+    optionalIntbox.emplace(42);
+    EXPECT_EQ(42, optionalIntbox->number);
+}
+
+TEST(OptionalTest, DestructorCalled)
+{
+    // Destroying a disengaged optional shouldn't do anything.
+    {
+        Optional<DestructionNotifier> optional;
+    }
+
+    // Destroying an engaged optional should call the destructor.
+    bool isDestroyed = false;
+    {
+        Optional<DestructionNotifier> optional;
+        optional.emplace(isDestroyed);
+        EXPECT_FALSE(isDestroyed);
+    }
+    EXPECT_TRUE(isDestroyed);
+}
+
+} // namespace
+} // namespace WTF