Collect active stylesheets and and apply asynchronously.

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
@@ skipping 686 matching lines @@
 
   document->mediaQueryAffectingValueChanged();
   document->setNeedsStyleRecalc(
       SubtreeStyleChange,
       StyleChangeReasonForTracing::create(StyleChangeReason::Zoom));
   document->updateStyleAndLayoutIgnorePendingStylesheets();
 }
 
 void LocalFrame::deviceScaleFactorChanged() {
   document()->mediaQueryAffectingValueChanged();
+  document()->setNeedsStyleRecalc(
+      SubtreeStyleChange,
+      StyleChangeReasonForTracing::create(StyleChangeReason::Zoom));
   for (Frame* child = tree().firstChild(); child;
        child = child->tree().nextSibling()) {
     if (child->isLocalFrame())
       toLocalFrame(child)->deviceScaleFactorChanged();
   }
 }
 
 double LocalFrame::devicePixelRatio() const {
   if (!m_host)
     return 0;
@@ skipping 222 matching lines @@
   if (m_frame && m_frame->client() && m_frame->client()->frameBlameContext())
     m_frame->client()->frameBlameContext()->Enter();
 }
 
 ScopedFrameBlamer::~ScopedFrameBlamer() {
   if (m_frame && m_frame->client() && m_frame->client()->frameBlameContext())
     m_frame->client()->frameBlameContext()->Leave();
 }
 
 }  // namespace blink