add HitTestCanvasResult Class instend of std::pair<Element*, String>

third_party/WebKit/Source/core/layout/HitTestCanvasResult.cpp

+// Copyright 2016 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 "HitTestCanvasResult.h"
+
+namespace blink {
+
+HitTestCanvasResult::HitTestCanvasResult(String id, Member<Element> control)
+    : m_id(id), m_control(control)
+{
+
+}
+
+String HitTestCanvasResult::getId() const
+{
+    return m_id;
+}
+
+Element* HitTestCanvasResult::getControl() const
+{
+    return m_control.get();
+};
+
+DEFINE_TRACE(HitTestCanvasResult)
+{
+    visitor->trace(m_control);
+}
+
+} // namespace blink