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.
@@ skipping 5195 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();

[esprehn, 2016/11/05 03:01:11]

Why do you need to call this here if you're also calling it inside setParent() ?

   }
 }
 
 Vector<IconURL> Document::iconURLs(int iconTypesMask) {
   IconURL firstFavicon;
   IconURL firstTouchIcon;
   IconURL firstTouchPrecomposedIcon;
   Vector<IconURL> secondaryIcons;
 
   // Start from the last child node so that icons seen later take precedence as
@@ skipping 1236 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