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 32 matching lines @@
   };
 
   static IntersectionObserver* create(const IntersectionObserverInit&,
                                       IntersectionObserverCallback&,
                                       ExceptionState&);
   static IntersectionObserver* create(const Vector<Length>& rootMargin,
                                       const Vector<float>& thresholds,
                                       Document*,
                                       std::unique_ptr<EventCallback>,
                                       ExceptionState& = ASSERT_NO_EXCEPTION);
+  // Observes any element/viewport ratio changes.
+  static IntersectionObserver* create(const Vector<Length>& rootMargin,
+                                      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);
   void disconnect(ExceptionState& = ASSERT_NO_EXCEPTION);
   HeapVector<Member<IntersectionObserverEntry>> takeRecords(ExceptionState&);
 
   // API attributes.
   Element* root() const;
@@ skipping 23 matching lines @@
   // TODO(skyostil): Move this setting to IntersectionObserverInit once the API
   // is finalized.
   void setInitialState(InitialState);
 
   DECLARE_TRACE();
 
  private:
   explicit IntersectionObserver(IntersectionObserverCallback&,
                                 Node&,
                                 const Vector<Length>& rootMargin,
-                                const Vector<float>& thresholds);
+                                const Vector<float>& thresholds,
+                                bool isObservingIntersection);

[miu, 2016/11/16 02:40:26]

naming: This is weird because the class name is IntersectionObserver and the
last argument is named |isObservingIntersection|. Maybe you meant something like
|observeViewportIntersection|?

[xjz, 2016/11/16 07:45:55]

Done.

   void clearWeakMembers(Visitor*);
 
   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