IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/IntersectionObserverRegistry.h

+// Copyright 2015 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 IntersectionObserverRegistry_h
+#define IntersectionObserverRegistry_h
+
+#include "core/dom/Element.h"
+#include "core/dom/IntersectionObserver.h"
+#include "platform/Timer.h"
+#include "platform/heap/Handle.h"
+#include "wtf/HashSet.h"
+#include "wtf/RefCounted.h"
+
+namespace blink {
+
+class Document;
+template<typename T> class Timer;
+
+class IntersectionObserverRegistry : public GarbageCollectedFinalized<IntersectionObserverRegistry> {
+public:
+    IntersectionObserverRegistry(Timer<Document>&);
+
+    void scheduleIntersectionObserverForDelivery(IntersectionObserver&);
+    void resumeSuspendedIntersectionObservers();
+    void deliverIntersectionObservations();
+    void computeTrackedIntersectionObservations();
+    void addTrackedObserver(IntersectionObserver&);
+    void removeTrackedObserversForRoot(Element*);
+
+    DECLARE_TRACE();
+
+private:
+    Timer<Document>& m_timer;
+    // IntersectionObservers for which this is the tracking document.
+    Member<IntersectionObserver::WeakHashSet> m_trackedIntersectionObservers;
+    // IntersectionObservers for which this is the execution context of the callback.
+    Member<IntersectionObserver::HashSet> m_activeIntersectionObservers;
+    Member<IntersectionObserver::HashSet> m_suspendedIntersectionObservers;
+};
+
+} // namespace blink
+
+#endif // IntersectionObservationRegistry_h