Intersection Observer first draft

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

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index 8e9c4e32f850ec619e8e9f382b61fd02d097c5b8..b186d190cfdc7cf6d54597566d3a0fcda5e3d187 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -125,6 +125,7 @@ class HTMLScriptElement;
 class HitTestRequest;
 class IdleRequestCallback;
 class InputDeviceCapabilities;
+class IntersectionObserver;
 class LayoutPoint;
 class LiveNodeListBase;
 class Locale;
@@ -173,6 +174,8 @@ struct IconURL;
 using MouseEventWithHitTestResults = EventWithHitTestResults<PlatformMouseEvent>;
 using ExceptionCode = int;
 
+using IntersectionObservers = WillBeHeapListHashSet<RefPtrWillBeMember<IntersectionObserver>>;
+
 enum StyleResolverUpdateMode {
     // Discards the StyleResolver and rebuilds it.
     FullStyleUpdate,
@@ -678,6 +681,9 @@ public:
     bool hasMutationObservers() const { return m_mutationObserverTypes; }
     void addMutationObserverTypes(MutationObserverOptions types) { m_mutationObserverTypes |= types; }
 
+    void activateIntersectionObserver(IntersectionObserver&);
+    void resumeSuspendedIntersectionObservers();
+
     void updateViewportDescription();
     void processReferrerPolicy(const String& policy);
 
@@ -1065,6 +1071,8 @@ protected:
     void lockCompatibilityMode() { m_compatibilityModeLocked = true; }
     ParserSynchronizationPolicy parserSynchronizationPolicy() const { return m_parserSyncPolicy; }
 
+    void deliverIntersectionObservationsTimerFired(Timer<Document>*);
+
 private:
     friend class IgnoreDestructiveWriteCountIncrementer;
     friend class NthIndexCache;
@@ -1330,6 +1338,10 @@ private:
     Timer<Document> m_loadEventDelayTimer;
     Timer<Document> m_pluginLoadingTimer;
 
+    Timer<Document> m_deliverIntersectionObservationsTimer;
+    IntersectionObservers m_activeIntersectionObservers;
+    IntersectionObservers m_suspendedIntersectionObservers;
+
     ViewportDescription m_viewportDescription;
     ViewportDescription m_legacyViewportDescription;
     Length m_viewportDefaultMinWidth;