Include viewport visibility checks for autoplay experiment.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 10 matching lines @@
 #include "config.h"
 #include "core/layout/LayoutView.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/editing/FrameSelection.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/html/HTMLIFrameElement.h"
+#include "core/html/HTMLVideoElement.h"
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutFlowThread.h"
 #include "core/layout/LayoutGeometryMap.h"
+#include "core/layout/LayoutMedia.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutQuote.h"
 #include "core/layout/LayoutScrollbarPart.h"
 #include "core/layout/compositing/DeprecatedPaintLayerCompositor.h"
 #include "core/page/Page.h"
 #include "core/paint/DeprecatedPaintLayer.h"
 #include "core/paint/ViewPainter.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "platform/TraceEvent.h"
 #include "platform/TracedValue.h"
@@ skipping 902 matching lines @@
     float scale = m_frameView ? m_frameView->frame().pageZoomFactor() : 1;
     return viewHeight(IncludeScrollbars) / scale;
 }
 
 void LayoutView::willBeDestroyed()
 {
     LayoutBlockFlow::willBeDestroyed();
     m_compositor.clear();
 }
 
+void LayoutView::registerMediaForPositionChangeNotification(LayoutMedia* media)

[esprehn, 2015/10/01 07:04:15]

reference

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

done, though the vector must still be LayoutMedia* and the callers now send
*this.  why is reference preferable here?

+{
+    if (!m_mediaForPositionNotification.contains(media))
+        m_mediaForPositionNotification.append(media);
+}
+
+void LayoutView::unregisterMediaForPositionChangeNotification(LayoutMedia* media)

[esprehn, 2015/10/01 07:04:15]

reference

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

ditto.

+{
+    size_t at = m_mediaForPositionNotification.find(media);
+    if (at != kNotFound)
+        m_mediaForPositionNotification.remove(at);
+}
+
+void LayoutView::sendMediaPositionChangeNotifications()
+{
+    for (auto& media : m_mediaForPositionNotification) {
+        media->notifyPositionMayHaveChanged();

[esprehn, 2015/10/01 07:04:15]

This isn't really the same timing as intersection observer, it would be on a
Timer, I think we should do that for this too otherwise you'll depend on the
synchronous dispatch which is bad

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

One of the objections to a prior iteration of this CL was setting timers too
often on scroll events.  those events happen less often than
sendMediaPositionChangeNotification() is called now.

plus, the callback does most of the real work on a (debounced) timer anyway. 
i'll leave it for now.  i believe it will work with the IntersectionObserver as
is.

+    }
+}
+
 } // namespace blink