Allow local root FrameView to be throttled

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 2357 matching lines @@
     if (phases == AllPhases)
         isUpdatingAllLifecyclePhasesScope.emplace(m_isUpdatingAllLifecyclePhases, true);
 
     // This must be called from the root frame, since it recurses down, not up.
     // Otherwise the lifecycles of the frames might be out of sync.
     ASSERT(m_frame->isLocalRoot());
 
     // Updating layout can run script, which can tear down the FrameView.
     RefPtrWillBeRawPtr<FrameView> protector(this);
 
+    if (shouldThrottleRendering()) {
+        updateViewportIntersectionsForSubtree();
+        return;
+    }
+
     updateStyleAndLayoutIfNeededRecursive();
     ASSERT(lifecycle().state() >= DocumentLifecycle::LayoutClean);
 
     if (phases == OnlyUpToLayoutClean) {
         updateViewportIntersectionsForSubtree();
         return;
     }
 
     if (LayoutView* view = layoutView()) {
         {
@@ skipping 1624 matching lines @@
     return m_hiddenForThrottling && m_crossOriginForThrottling;
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(layoutView());
     return *layoutView();
 }
 
 } // namespace blink