Monitor the intersection of video and viewport.

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

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.h
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.h b/third_party/WebKit/Source/core/dom/IntersectionObserver.h
index 3281fcea96352ef256fc00bd74383250e40b02ac..2ed72a72fa4fd37dda87c6b8abe028426b7257dd 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObserver.h
+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.h
@@ -50,6 +50,11 @@ class CORE_EXPORT IntersectionObserver final
                                       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.
@@ -93,7 +98,8 @@ class CORE_EXPORT IntersectionObserver final
   explicit IntersectionObserver(IntersectionObserverCallback&,
                                 Node&,
                                 const Vector<Length>& rootMargin,
-                                const Vector<float>& thresholds);
+                                const Vector<float>& thresholds,
+                                bool isObservingRatio);
   void clearWeakMembers(Visitor*);
 
   Member<IntersectionObserverCallback> m_callback;
@@ -106,6 +112,7 @@ class CORE_EXPORT IntersectionObserver final
   Length m_bottomMargin;
   Length m_leftMargin;
   InitialState m_initialState;
+  bool m_observeElementViewportRatio = false;

[miu, 2016/11/11 08:18:33]

Since this is initialized in the ctor, you don't need the " = false" here.

[xjz, 2016/11/11 17:57:48]

Done.

 };
 
 }  // namespace blink