MouseWheelEventManager is added to handle wheel events.

third_party/WebKit/Source/core/input/MouseWheelEventManager.h

+// Copyright 2017 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 MouseWheelEventManager_h
+#define MouseWheelEventManager_h
+
+#include "platform/heap/Handle.h"
+#include "platform/heap/Visitor.h"
+#include "public/platform/WebInputEventResult.h"
+
+namespace blink {
+
+class LocalFrame;
+class ScrollManager;
+class WebMouseWheelEvent;
+
+class MouseWheelEventManager final
+    : public GarbageCollectedFinalized<MouseWheelEventManager> {
+  WTF_MAKE_NONCOPYABLE(MouseWheelEventManager);
+
+ public:
+  explicit MouseWheelEventManager(LocalFrame&, ScrollManager&);
+  DECLARE_TRACE();
+
+  WebInputEventResult HandleWheelEvent(const WebMouseWheelEvent&);
+
+ private:
+  const Member<LocalFrame> frame_;
+  Member<ScrollManager> scroll_manager_;
+};
+
+}  // namespace blink
+
+#endif  // MouseWheelEventManager_h