Add IntersectionObserverEntry.intersectionRatio attribute.

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

 // 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.
 
 #include "core/dom/IntersectionObservation.h"
 
 #include "core/dom/ElementRareData.h"
 #include "core/dom/IntersectionObserver.h"
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBox.h"
@@ skipping 180 matching lines @@
     //     only two states are recognized:
     //     - 0 means not intersecting.
     //     - 1 means intersecting.
     //     No other threshold crossings are possible.
     //   - Otherwise:
     //     - If root and target do not intersect, the threshold index is 0.
     //     - If root and target intersect but the intersection has zero-area (i.e., they
     //       have a coincident edge or corner), we consider the intersection to have
     //       "crossed" a zero threshold, but not crossed any non-zero threshold.
     unsigned newThresholdIndex;
+    float newVisibleRatio = 0;
     if (geometry.targetRect.isEmpty()) {
         newThresholdIndex = geometry.doesIntersect ? 1 : 0;
     } else if (!geometry.doesIntersect) {
         newThresholdIndex = 0;
     } else {
         float intersectionArea = geometry.intersectionRect.size().width().toFloat() * geometry.intersectionRect.size().height().toFloat();
         float targetArea = geometry.targetRect.size().width().toFloat() * geometry.targetRect.size().height().toFloat();
-        float newVisibleRatio = intersectionArea / targetArea;
+        newVisibleRatio = intersectionArea / targetArea;
         newThresholdIndex = observer().firstThresholdGreaterThan(newVisibleRatio);
     }
     if (m_lastThresholdIndex != newThresholdIndex) {
         IntRect snappedRootBounds = pixelSnappedIntRect(geometry.rootRect);
         IntRect* rootBoundsPointer = m_shouldReportRootBounds ? &snappedRootBounds : nullptr;
         IntersectionObserverEntry* newEntry = new IntersectionObserverEntry(
             timestamp,
+            newVisibleRatio,
             pixelSnappedIntRect(geometry.targetRect),
             rootBoundsPointer,
             pixelSnappedIntRect(geometry.intersectionRect),
             target());
         observer().enqueueIntersectionObserverEntry(*newEntry);
     }
     setLastThresholdIndex(newThresholdIndex);
 }
 
 void IntersectionObservation::disconnect()
@@ skipping 10 matching lines @@
     m_observer.clear();
 }
 
 DEFINE_TRACE(IntersectionObservation)
 {
     visitor->trace(m_observer);
     visitor->trace(m_target);
 }
 
 } // namespace blink