Include viewport visibility checks for autoplay experiment.

Source/core/layout/LayoutMedia.cpp

Index: Source/core/layout/LayoutMedia.cpp
diff --git a/Source/core/layout/LayoutMedia.cpp b/Source/core/layout/LayoutMedia.cpp
index 374c4b1889cb25e1e8043d9c099085f857c5906d..4d7740e9711694e47f555bef52e71af1825defba 100644
--- a/Source/core/layout/LayoutMedia.cpp
+++ b/Source/core/layout/LayoutMedia.cpp
@@ -35,6 +35,8 @@ namespace blink {
 
 LayoutMedia::LayoutMedia(HTMLMediaElement* video)
     : LayoutImage(video)
+    , m_registeredForPositionChangeNotifications(false)
+    , m_wantPositionChangeNotifications(false)
 {
     setImageResource(LayoutImageResource::create());
 }
@@ -119,4 +121,60 @@ void LayoutMedia::paintReplaced(const PaintInfo&, const LayoutPoint&)
 {
 }
 
+void LayoutMedia::willBeDestroyed()
+{
+    updatePositionChangeRegistration(false);
+    LayoutImage::willBeDestroyed();
+}
+
+void LayoutMedia::insertedIntoTree()
+{
+    LayoutImage::insertedIntoTree();
+
+    // Note that if we don't want them and aren't registered, then this
+    // will do nothing.
+    updatePositionChangeRegistration(m_wantPositionChangeNotifications);
+}
+
+void LayoutMedia::willBeRemovedFromTree()
+{
+    // Note that if we don't want them and/or aren't registered, then this
+    // will do nothing.
+    updatePositionChangeRegistration(false);
+
+    LayoutImage::willBeRemovedFromTree();
+}
+
+void LayoutMedia::notifyPositionMayHaveChanged()
+{
+    // Tell our element about it.
+    if (HTMLMediaElement* element = mediaElement())
+        element->notifyPositionMayHaveChanged();
+}
+
+void LayoutMedia::updatePositionChangeRegistration(bool doRegister)
+{
+    // If we don't have a view, then take no action.
+    if (!view())
+        return;
+
+    // If our registration state matches the incoming state, then no work
+    // is needed.
+    if (doRegister == m_registeredForPositionChangeNotifications)
+        return;
+
+    if (doRegister)
+        view()->registerMediaForPositionChangeNotification(this);
+    else
+        view()->unregisterMediaForPositionChangeNotification(this);
+
+    m_registeredForPositionChangeNotifications = doRegister;
+}
+
+void LayoutMedia::setRequestPositionUpdates(bool want)
+{
+    m_wantPositionChangeNotifications = want;
+    updatePositionChangeRegistration(m_wantPositionChangeNotifications);
+}
+
 } // namespace blink