Include viewport visibility checks for autoplay experiment.

third_party/WebKit/Source/core/layout/LayoutView.h

Index: third_party/WebKit/Source/core/layout/LayoutView.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutView.h b/third_party/WebKit/Source/core/layout/LayoutView.h
index 6772b76e061f5d27b95485512cea58f1c990a9c9..01f4d270743096952fa90c9b05969191074a2a0f 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.h
+++ b/third_party/WebKit/Source/core/layout/LayoutView.h
@@ -40,6 +40,7 @@ namespace blink {
 
 class DeprecatedPaintLayerCompositor;
 class LayoutQuote;
+class LayoutMedia;
 
 // LayoutView is the root of the layout tree and the Document's LayoutObject.
 //
@@ -198,6 +199,15 @@ public:
     // It is very likely you do not want to call this method.
     void setShouldDoFullPaintInvalidationForViewAndAllDescendants();
 
+    // Some LayoutMedias want to know about their viewport visibility for
+    // crbug.com/487345,402044 .  This facility will be removed once those
+    // experiments complete.
+    void registerMediaForPositionChangeNotification(LayoutMedia*);

[ojan, 2015/10/01 06:14:26]

Please add:
TODO(ojan): Merge this with IntersectionObserver once it lands.

[liberato (no reviews please), 2015/10/01 22:49:03]

Done.

+    void unregisterMediaForPositionChangeNotification(LayoutMedia*);
+    // Notify all registered LayoutMedias that their position on-screen might
+    // have changed.
+    void sendMediaPositionChangeNotifications();
+
 private:
     void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override;
 
@@ -260,6 +270,8 @@ private:
     unsigned m_hitTestCount;
     unsigned m_hitTestCacheHits;
     OwnPtrWillBePersistent<HitTestCache> m_hitTestCache;
+
+    Vector<LayoutMedia*> m_mediaForPositionNotification;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutView, isLayoutView());