Track event handlers on windows

Source/core/frame/EventHandlerRegistry.h

Index: Source/core/frame/EventHandlerRegistry.h
diff --git a/Source/core/frame/EventHandlerRegistry.h b/Source/core/frame/EventHandlerRegistry.h
index c462780348207352d934e05ea2154608acaecc5d..e3e9b5ee73566c43041cc3cddd587b7fc901a03a 100644
--- a/Source/core/frame/EventHandlerRegistry.h
+++ b/Source/core/frame/EventHandlerRegistry.h
@@ -6,8 +6,10 @@
 #define EventHandlerRegistry_h
 
 #include "core/events/Event.h"
+#include "core/frame/DOMWindowLifecycleObserver.h"
 #include "core/frame/FrameHost.h"
 #include "wtf/HashCountedSet.h"
+#include "wtf/HashMap.h"
 
 namespace WebCore {
 
@@ -87,8 +89,24 @@ private:
 
     void checkConsistency() const;
 
+    class WindowObserver: public DOMWindowLifecycleObserver {
+    public:
+        WindowObserver(EventHandlerRegistry&, DOMWindow&);
+        virtual ~WindowObserver();
+
+        // Inherited from DOMWindowLifecycleObserver
+        virtual void didAddEventListener(DOMWindow*, const AtomicString&) OVERRIDE;
+        virtual void didRemoveEventListener(DOMWindow*, const AtomicString&) OVERRIDE;
+        virtual void didRemoveAllEventListeners(DOMWindow*) OVERRIDE;
+
+    private:
+        EventHandlerRegistry& m_registry;
+    };
+
     FrameHost& m_frameHost;
     EventTargetSet m_targets[EventHandlerClassCount];
+
+    HashMap<DOMWindow*, OwnPtr<WindowObserver> > m_windowObservers;
 };
 
 } // namespace WebCore