Expose scroll customization for touch to JS (behind REF).

Source/core/page/scrolling/ScrollStateCallback.cpp

+// 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 "core/page/scrolling/ScrollStateCallback.h"
+
+#include "bindings/core/v8/V8Element.h"
+#include "bindings/core/v8/V8ScrollState.h"
+
+namespace blink {
+
+ScrollStateCallback::ScrollStateCallback()
+    : m_callbackType(CallbackType::UNSET)
+{
+}
+
+void ScrollStateCallback::handleEventForElement(Element& targetElement, ScrollState* scrollState)
+{
+    m_targetElement = &targetElement;

[haraken, 2015/06/30 07:08:30]

Instead of storing m_targetElement to ScrollStateCallback, how about just
passing the target element to handleEvent()?

+    handleEvent(scrollState);
+    m_targetElement = nullptr;
+}
+
+} // namespace blink