Set rootBounds to null for cross-origin observations.

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

 // 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.
 
 #ifndef IntersectionObserverEntry_h
 #define IntersectionObserverEntry_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/dom/ClientRect.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class Element;
 
 class IntersectionObserverEntry final : public GarbageCollectedFinalized<IntersectionObserverEntry>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    IntersectionObserverEntry(double timestamp, const IntRect& boundingClientRect, const IntRect& rootBounds, const IntRect& intersectionRect, Element*);
+    IntersectionObserverEntry(double timestamp, const IntRect& boundingClientRect, const IntRect* rootBounds, const IntRect& intersectionRect, Element*);
     ~IntersectionObserverEntry();
 
     double time() const { return m_time; }
     ClientRect* boundingClientRect() const { return m_boundingClientRect; }
     ClientRect* rootBounds() const { return m_rootBounds; }
     ClientRect* intersectionRect() const { return m_intersectionRect; }
     Element* target() const { return m_target.get(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     double m_time;
     Member<ClientRect> m_boundingClientRect;
     Member<ClientRect> m_rootBounds;
     Member<ClientRect> m_intersectionRect;
     RefPtrWillBeMember<Element> m_target;
 };
 
 } // namespace blink
 
 #endif // IntersectionObserverEntry_h