Monitor the intersection of video and viewport.

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

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
index 60be0837ef1f6001b6cdf4493d28ebe1097ff8b6..2bfda308d700a92cd534e3f25ac579e0f6fc8631 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
@@ -188,8 +188,13 @@ IntersectionObserver* IntersectionObserver::create(
 
   IntersectionObserverCallbackImpl* intersectionObserverCallback =
       new IntersectionObserverCallbackImpl(document, std::move(callback));
-  return new IntersectionObserver(*intersectionObserverCallback, *root,
-                                  rootMargin, thresholds);
+  if (thresholds.isEmpty()) {
+    return new ViewportIntersectionObserver(*intersectionObserverCallback,
+                                            *root, rootMargin);
+  } else {
+    return new IntersectionObserver(*intersectionObserverCallback, *root,
+                                    rootMargin, thresholds);
+  }
 }
 
 IntersectionObserver::IntersectionObserver(
@@ -235,6 +240,8 @@ IntersectionObserver::IntersectionObserver(
       *this);
 }
 
+IntersectionObserver::~IntersectionObserver() {}
+
 void IntersectionObserver::clearWeakMembers(Visitor* visitor) {
   if (ThreadHeap::isHeapObjectAlive(m_root))
     return;
@@ -280,7 +287,7 @@ void IntersectionObserver::observe(Element* target,
   }
 
   IntersectionObservation* observation =
-      new IntersectionObservation(*this, *target, shouldReportRootBounds);
+      createObservation(*target, shouldReportRootBounds);
   target->ensureIntersectionObserverData().addObservation(*observation);
   m_observations.add(observation);
 
@@ -445,6 +452,12 @@ void IntersectionObserver::deliver() {
   m_callback->handleEvent(entries, *this);
 }
 
+IntersectionObservation* IntersectionObserver::createObservation(
+    Element& target,
+    bool shouldReportRootBounds) {
+  return new IntersectionObservation(*this, target, shouldReportRootBounds);
+}
+
 DEFINE_TRACE(IntersectionObserver) {
   visitor->template registerWeakMembers<
       IntersectionObserver, &IntersectionObserver::clearWeakMembers>(this);
@@ -453,4 +466,18 @@ DEFINE_TRACE(IntersectionObserver) {
   visitor->trace(m_entries);
 }
 
+ViewportIntersectionObserver::ViewportIntersectionObserver(
+    IntersectionObserverCallback& callback,
+    Node& node,
+    const Vector<Length>& rootMargin)
+    : IntersectionObserver(callback, node, rootMargin, Vector<float>()) {}
+
+ViewportIntersectionObserver::~ViewportIntersectionObserver() {}
+
+IntersectionObservation* ViewportIntersectionObserver::createObservation(
+    Element& target,
+    bool) {
+  return new ViewportIntersectionObservation(*this, target);
+}
+
 }  // namespace blink