Use intersection observer to control frame throttling

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 4867 matching lines @@
     if (!isRenderingReady())
         return;
     if (LocalFrame* frame = this->frame()) {
         // Avoid pumping frames for the initially empty document.
         if (!frame->loader().stateMachine()->committedFirstRealDocumentLoad())
             return;
         // The compositor will "defer commits" for the main frame until we
         // explicitly request them.
         if (frame->isMainFrame())
             frame->page()->chromeClient().beginLifecycleUpdates();
+        if (frame->view())
+            frame->view()->setupRenderThrottling();

[dgrogan, 2016/09/21 17:55:56]

Just for my understanding, why call this here in addition to
FrameView::setParent? Won't setParent cover all non-top-level frames?

     }
 }
 
 Vector<IconURL> Document::iconURLs(int iconTypesMask)
 {
     IconURL firstFavicon;
     IconURL firstTouchIcon;
     IconURL firstTouchPrecomposedIcon;
     Vector<IconURL> secondaryIcons;
 
@@ skipping 1191 matching lines @@
 }
 
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().getString().utf8().data());
 }
 #endif