IntersectionObserver: second cut.

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

Index: third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.h
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.h b/third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.h
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+// 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 IntersectionObservationRegistry_h
+#define IntersectionObservationRegistry_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;
+
+typedef WillBeHeapHashSet<RefPtrWillBeMember<IntersectionObserver>> IntersectionObserverHashSet;
+
+class IntersectionObservationRegistry {
+public:
+    IntersectionObservationRegistry(Timer<Document>&);
+    virtual ~IntersectionObservationRegistry();
+
+    void activateIntersectionObserver(IntersectionObserver&);
+    void resumeSuspendedIntersectionObservers();
+    void deliverIntersectionObservations();
+    void clearIntersectionObservations();
+    void computeIntersectionObservations();
+    void addObservation(IntersectionObservation&);
+    void removeObservation(IntersectionObservation&);
+
+private:
+    Timer<Document>& m_timer;
+    IntersectionObserverHashSet m_activeIntersectionObservers;
+    IntersectionObserverHashSet m_suspendedIntersectionObservers;
+    IntersectionObservation::HashSet m_intersectionObservations;
+};
+
+} // namespace blink
+
+#endif // IntersectionObservationRegistry_h