Monitor the intersection of video and viewport.

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

Index: third_party/WebKit/Source/core/dom/IntersectionObservation.cpp
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObservation.cpp b/third_party/WebKit/Source/core/dom/IntersectionObservation.cpp
index c9c04457e5ea67c7f176de9f8542466870e0c392..8d6a7b07776c07c08b564db4881aedca8833163a 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObservation.cpp
+++ b/third_party/WebKit/Source/core/dom/IntersectionObservation.cpp
@@ -22,6 +22,8 @@ IntersectionObservation::IntersectionObservation(IntersectionObserver& observer,
       m_shouldReportRootBounds(shouldReportRootBounds),
       m_lastThresholdIndex(0) {}
 
+IntersectionObservation::~IntersectionObservation() {}
+
 void IntersectionObservation::applyRootMargin(LayoutRect& rect) const {
   if (m_shouldReportRootBounds)
     m_observer->applyRootMargin(rect);
@@ -255,4 +257,37 @@ DEFINE_TRACE(IntersectionObservation) {
   visitor->trace(m_target);
 }
 
+IntersectViewportRatioObservation::IntersectViewportRatioObservation(
+    IntersectionObserver& observer,
+    Element& element)
+    : IntersectionObservation(observer, element, true) {}
+
+IntersectViewportRatioObservation::~IntersectViewportRatioObservation() {}
+
+void IntersectViewportRatioObservation::computeIntersectionObservations(
+    DOMHighResTimeStamp timestamp) {
+  IntersectionGeometry geometry;
+  if (!computeGeometry(geometry))
+    return;
+
+  float newVisibleRatio = 0;
+  if (!geometry.targetRect.isEmpty() && geometry.doesIntersect) {
+    float intersectionArea =
+        geometry.intersectionRect.size().width().toFloat() *
+        geometry.intersectionRect.size().height().toFloat();
+    float rootArea = geometry.rootRect.size().width().toFloat() *
+                     geometry.rootRect.size().height().toFloat();
+    newVisibleRatio = intersectionArea / rootArea;
+  }
+  if (newVisibleRatio != m_lastVisibleRatio) {
+    IntRect snappedRootBounds = pixelSnappedIntRect(geometry.rootRect);
+    IntersectionObserverEntry* newEntry = new IntersectionObserverEntry(
+        timestamp, newVisibleRatio, pixelSnappedIntRect(geometry.targetRect),
+        &snappedRootBounds, pixelSnappedIntRect(geometry.intersectionRect),
+        target());
+    observer().enqueueIntersectionObserverEntry(*newEntry);
+    m_lastVisibleRatio = newVisibleRatio;
+  }
+}
+
 }  // namespace blink