Refactor IntersectionGeometry class and move it to core/layout.

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 2ae1556fc10ddca7a031867902c3f74dde19c9c3..724c4312e55bd32fe530d9023a8e2c4d92af009c 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObservation.cpp
+++ b/third_party/WebKit/Source/core/dom/IntersectionObservation.cpp
@@ -6,18 +6,16 @@
 
 #include "core/dom/ElementRareData.h"
 #include "core/dom/IntersectionObserver.h"
+#include "core/layout/IntersectionGeometry.h"
 
 namespace blink {
 
-IntersectionObservation::IntersectionObservation(
-    IntersectionObserver& observer,
-    Element& target,
-    IntersectionGeometry::ReportRootBounds shouldReportRootBounds)
+IntersectionObservation::IntersectionObservation(IntersectionObserver& observer,
+                                                 Element& target,
+                                                 bool shouldReportRootBounds)
     : m_observer(observer),
       m_target(&target),
-      m_shouldReportRootBounds(
-          shouldReportRootBounds ==
-          IntersectionGeometry::ReportRootBounds::kShouldReportRootBounds),
+      m_shouldReportRootBounds(shouldReportRootBounds),
       m_lastThresholdIndex(0) {}
 
 void IntersectionObservation::computeIntersectionObservations(
@@ -29,11 +27,10 @@ void IntersectionObservation::computeIntersectionObservations(
   rootMargin[1] = m_observer->rightMargin();
   rootMargin[2] = m_observer->bottomMargin();
   rootMargin[3] = m_observer->leftMargin();
+  Node* rootNode = m_observer->rootNode();
   IntersectionGeometry geometry(
-      m_observer->rootNode(), target(), rootMargin,
-      m_shouldReportRootBounds
-          ? IntersectionGeometry::ReportRootBounds::kShouldReportRootBounds
-          : IntersectionGeometry::ReportRootBounds::kShouldNotReportRootBounds);
+      rootNode && !rootNode->isDocumentNode() ? toElement(rootNode) : nullptr,
+      *target(), rootMargin, m_shouldReportRootBounds);
   geometry.computeGeometry();
 
   // Some corner cases for threshold index: