IntersectionObserver: second cut.

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

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.h
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.h b/third_party/WebKit/Source/core/dom/IntersectionObserver.h
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+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.h
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+// Copyright 2016 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/IntersectionObservation.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 IntersectionObserverInit;
+
+class IntersectionObserver final : public GarbageCollectedFinalized<IntersectionObserver>, public ScriptWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+
+public:
+    static IntersectionObserver* create(const IntersectionObserverInit&, IntersectionObserverCallback&, ExceptionState&);
+    static void resumeSuspendedObservers();
+
+    // API methods
+    void observe(Element*, ExceptionState&);
+    void unobserve(Element*, ExceptionState&);
+    void disconnect();
+    HeapVector<Member<IntersectionObserverEntry>> takeRecords();
+
+    Element* root() { return m_root.get(); }
+    LayoutObject* rootLayoutObject();
+    bool isDescendantOfRoot(const Element*) const;
+    void computeIntersectionObservations(double timestamp);
+    void disconnect(IntersectionObservation&);
+    void enqueueIntersectionObserverEntry(IntersectionObserverEntry&);
+    void applyRootMargin(LayoutRect&) const;
+    unsigned firstThresholdGreaterThan(float ratio) const;
+    bool shouldBeSuspended() const;
+    void deliver();
+    void setActive(bool);
+    bool hasPercentMargin() const;
+    const Length& topMargin() const { return m_topMargin; }
+    const Length& rightMargin() const { return m_rightMargin; }
+    const Length& bottomMargin() const { return m_bottomMargin; }
+    const Length& leftMargin() const { return m_leftMargin; }
+
+#if !ENABLE(OILPAN)
+    void dispose();
+#endif
+
+    DECLARE_TRACE();
+
+private:
+    explicit IntersectionObserver(IntersectionObserverCallback&, Element&, const Vector<Length>& rootMargin, const Vector<float>& thresholds);
+
+    void checkRootAndDetachIfNeeded();
+
+    Member<IntersectionObserverCallback> m_callback;
+    WeakPtrWillBeWeakMember<Element> m_root;
+    HeapHashSet<WeakMember<IntersectionObservation>> m_observations;
+    HeapVector<Member<IntersectionObserverEntry>> m_entries;
+    Vector<float> m_thresholds;
+    Length m_topMargin;
+    Length m_rightMargin;
+    Length m_bottomMargin;
+    Length m_leftMargin;
+};
+
+} // namespace blink
+
+#endif // IntersectionObserver_h