Migrate wheel events to EventHandlerRegistry

Source/core/frame/EventHandlerRegistry.h

 // Copyright 2014 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 EventHandlerRegistry_h
 #define EventHandlerRegistry_h
 
 #include "core/events/Event.h"
 #include "core/frame/FrameHost.h"
 #include "wtf/HashCountedSet.h"
 
 namespace WebCore {
 
 typedef HashCountedSet<EventTarget*> EventTargetSet;
 
 // Registry for keeping track of event handlers. Note that only handlers on
 // documents that can be rendered or can receive input (i.e., are attached to a
 // FrameHost) are registered here.
 class EventHandlerRegistry FINAL : public NoBaseWillBeGarbageCollectedFinalized<EventHandlerRegistry> {
 public:
     explicit EventHandlerRegistry(FrameHost&);
     virtual ~EventHandlerRegistry();
 
     // Supported event handler classes. Note that each one may correspond to
     // multiple event types.
     enum EventHandlerClass {
         ScrollEvent,
+        WheelEvent,
 #if ASSERT_ENABLED
         // Additional event categories for verifying handler tracking logic.
         EventsForTesting,
 #endif
         EventHandlerClassCount, // Must be the last entry.
     };
 
     // Returns true if the FrameHost has event handlers of the specified class.
     bool hasEventHandlers(EventHandlerClass) const;
 
@@ skipping 48 matching lines @@
 
     void checkConsistency() const;
 
     FrameHost& m_frameHost;
     EventTargetSet m_targets[EventHandlerClassCount];
 };
 
 } // namespace WebCore
 
 #endif // EventHandlerRegistry_h