Intersection Observer first draft

Source/core/dom/IntersectionObserver.h

Index: Source/core/dom/IntersectionObserver.h
diff --git a/Source/core/dom/IntersectionObserver.h b/Source/core/dom/IntersectionObserver.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 IntersectionObserver_h
+#define IntersectionObserver_h
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/Element.h"
+#include "core/dom/IntersectionObserverEntry.h"
+#include "platform/heap/Handle.h"
+#include "wtf/HashSet.h"
+#include "wtf/RefCounted.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class ExceptionState;
+class IntersectionObserverCallback;
+class IntersectionObserver;
+class IntersectionObserverInit;
+
+using IntersectionObserverEntryVector = WillBeHeapVector<RefPtrWillBeMember<IntersectionObserverEntry>>;
+using IntersectionObserverTargetVector = WillBeHeapVector<RefPtrWillBeWeakMember<Element>>;
+
+class IntersectionObserver final : public RefCountedWillBeGarbageCollectedFinalized<IntersectionObserver>, public ScriptWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+    friend class Document;
+public:
+    static PassRefPtrWillBeRawPtr<IntersectionObserver> create(Document*, PassOwnPtrWillBeRawPtr<IntersectionObserverCallback>);
+    static void resumeSuspendedObservers();
+
+    ~IntersectionObserver();
+
+    void observe(Element*, const IntersectionObserverInit&, ExceptionState&);
+    void disconnect();
+    IntersectionObserverEntryVector takeRecords();
+
+    void enqueueIntersectionObserverEntry(PassRefPtrWillBeRawPtr<IntersectionObserverEntry>);
+
+    // Eagerly finalized as destructor accesses heap object members.
+    EAGERLY_FINALIZE();
+    DECLARE_TRACE();
+
+private:
+    explicit IntersectionObserver(Document*, PassOwnPtrWillBeRawPtr<IntersectionObserverCallback>);
+    void deliver();
+    bool shouldBeSuspended() const;
+
+    OwnPtrWillBeMember<IntersectionObserverCallback> m_callback;
+    RawPtrWillBeWeakMember<Document> m_document;
+    IntersectionObserverEntryVector m_entries;
+    IntersectionObserverTargetVector m_targets;
+};
+
+} // namespace blink
+
+#endif // IntersectionObserver_h