Monitor the intersection of video and viewport.

third_party/WebKit/Source/core/dom/IntersectionObserver.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 IntersectionObserver_h
 #define IntersectionObserver_h
 
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/dom/IntersectionObservation.h"
@@ skipping 27 matching lines @@
   // delivered. kAuto means the initial observation will always get sent.
   enum class InitialState {
     // TODO(skyostil): Add support for kVisible.
     kAuto,
     kHidden,
   };
 
   static IntersectionObserver* create(const IntersectionObserverInit&,
                                       IntersectionObserverCallback&,
                                       ExceptionState&);
+  // Observes any changes on intersection rect when |thresholds| is empty.
   static IntersectionObserver* create(const Vector<Length>& rootMargin,
                                       const Vector<float>& thresholds,
                                       Document*,
                                       std::unique_ptr<EventCallback>,
                                       ExceptionState& = ASSERT_NO_EXCEPTION);
   static void resumeSuspendedObservers();
 
   // API methods.
   void observe(Element*, ExceptionState& = ASSERT_NO_EXCEPTION);
   void unobserve(Element*, ExceptionState& = ASSERT_NO_EXCEPTION);
@@ skipping 41 matching lines @@
   Member<IntersectionObserverCallback> m_callback;
   WeakMember<Node> m_root;
   HeapLinkedHashSet<WeakMember<IntersectionObservation>> m_observations;
   HeapVector<Member<IntersectionObserverEntry>> m_entries;
   Vector<float> m_thresholds;
   Length m_topMargin;
   Length m_rightMargin;
   Length m_bottomMargin;
   Length m_leftMargin;
   InitialState m_initialState;
+  bool m_observeViewportIntersection;
 };
 
 }  // namespace blink
 
 #endif  // IntersectionObserver_h