IntersectionObserver: second cut.

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

Index: third_party/WebKit/Source/core/dom/ElementRareData.h
diff --git a/third_party/WebKit/Source/core/dom/ElementRareData.h b/third_party/WebKit/Source/core/dom/ElementRareData.h
index 5e27cfe6ef0a797ef74015199dba900aba584b20..5dc80468be6485b01a45842036b9050e463371a1 100644
--- a/third_party/WebKit/Source/core/dom/ElementRareData.h
+++ b/third_party/WebKit/Source/core/dom/ElementRareData.h
@@ -25,6 +25,8 @@
 #include "core/animation/ElementAnimations.h"
 #include "core/dom/Attr.h"
 #include "core/dom/DatasetDOMStringMap.h"
+#include "core/dom/IntersectionObservation.h"
+#include "core/dom/IntersectionObserver.h"
 #include "core/dom/NamedNodeMap.h"
 #include "core/dom/NodeRareData.h"
 #include "core/dom/PseudoElement.h"
@@ -33,7 +35,9 @@
 #include "core/html/ClassList.h"
 #include "core/style/StyleInheritedData.h"
 #include "platform/heap/Handle.h"
+#include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
+#include "wtf/WeakPtr.h"
 
 namespace blink {
 
@@ -107,6 +111,33 @@ public:
         m_elementAnimations = elementAnimations;
     }
 
+    bool hasIntersectionObservation() const
+    {
+        return m_intersectionObservations && m_intersectionObservations->size();
+    }
+
+    IntersectionObservation::HashSet& intersectionObservations()
+    {
+        if (!m_intersectionObservations)
+            m_intersectionObservations = new IntersectionObservation::HashSet();
+        return *m_intersectionObservations;
+    }
+
+    void deactivateAllIntersectionObservations()
+    {
+        if (!m_intersectionObservations)
+            return;
+        for (auto& observation: *m_intersectionObservations)
+            observation->setActive(false);
+    }
+
+    WeakPtr<Element> createWeakPtr(Element* element)
+    {
+        if (!m_weakPointerFactory)
+            m_weakPointerFactory = adoptPtrWillBeNoop(new WeakPtrFactory<Element>(element));
+        return m_weakPointerFactory->createWeakPtr();
+    }
+
     bool hasPseudoElements() const;
     void clearPseudoElements();
 
@@ -141,8 +172,13 @@ private:
     OwnPtrWillBeMember<ElementShadow> m_shadow;
     OwnPtrWillBeMember<NamedNodeMap> m_attributeMap;
     OwnPtrWillBeMember<AttrNodeList> m_attrNodeList;
-    PersistentWillBeMember<ElementAnimations> m_elementAnimations;
     OwnPtrWillBeMember<InlineCSSStyleDeclaration> m_cssomWrapper;
+    OwnPtrWillBeMember<WeakPtrFactory<Element>> m_weakPointerFactory;
+
+    PersistentWillBeMember<ElementAnimations> m_elementAnimations;
+    // Note that m_intersectionObservers will contain both observers for which this element is target,
+    // and observers for which this element is root.  To tell them apart, check (observer->root() == element).
+    PersistentWillBeMember<IntersectionObservation::HashSet> m_intersectionObservations;
 
     RefPtr<ComputedStyle> m_computedStyle;
     RefPtrWillBeMember<CustomElementDefinition> m_customElementDefinition;