Enumerate the return value of dispatchEvent so it is clear.

third_party/WebKit/Source/core/events/WheelEvent.h

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef WheelEvent_h
 #define WheelEvent_h
 
 #include "core/CoreExport.h"
-#include "core/events/EventDispatchMediator.h"
 #include "core/events/MouseEvent.h"
 #include "core/events/WheelEventInit.h"
 #include "platform/geometry/FloatPoint.h"
 
 namespace blink {
 
 class PlatformWheelEvent;
 
 class CORE_EXPORT WheelEvent final : public MouseEvent {
     DEFINE_WRAPPERTYPEINFO();
@@ skipping 65 matching lines @@
     double m_deltaZ;
     unsigned m_deltaMode;
     bool m_canScroll;
     int m_resendingPluginId;
     bool m_hasPreciseScrollingDeltas;
     RailsMode m_railsMode;
 };
 
 DEFINE_EVENT_TYPE_CASTS(WheelEvent);
 
-class WheelEventDispatchMediator final : public EventDispatchMediator {
-public:
-    static PassRefPtrWillBeRawPtr<WheelEventDispatchMediator> create(PassRefPtrWillBeRawPtr<WheelEvent>);
-
-private:
-    explicit WheelEventDispatchMediator(PassRefPtrWillBeRawPtr<WheelEvent>);
-    WheelEvent& event() const;
-    bool dispatchEvent(EventDispatcher&) const override;
-};
-
 } // namespace blink
 
 #endif // WheelEvent_h