[Oilpan] Fix wrong usage of HeapCountedSet<EventTarget*>

third_party/WebKit/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/CoreExport.h"
 #include "core/frame/FrameHost.h"
 #include "wtf/HashCountedSet.h"
 
 namespace blink {
 
 class Document;
 class EventTarget;
 
-typedef HashCountedSet<EventTarget*> EventTargetSet;
+// EventHandlerRegistry::m_targets is handled manually in clearWeakMembers(),
+// so its type can be HeapHashCountedSet<Member<>>, but we use WeakMember<> in this
+// alias for future other use cases.
+using EventTargetSet = WillBeHeapHashCountedSet<RawPtrWillBeWeakMember<EventTarget>>;
 
 // 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 CORE_EXPORT EventHandlerRegistry final : public NoBaseWillBeGarbageCollectedFinalized<EventHandlerRegistry> {
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(EventHandlerRegistry);
 public:
     explicit EventHandlerRegistry(FrameHost&);
     virtual ~EventHandlerRegistry();
 
@@ skipping 71 matching lines @@
 
     void checkConsistency() const;
 
     RawPtrWillBeMember<FrameHost> m_frameHost;
     EventTargetSet m_targets[EventHandlerClassCount];
 };
 
 } // namespace blink
 
 #endif // EventHandlerRegistry_h