Web Animations CSS: Unfreeze AnimationClock if sampling timelines does not trigger style recalc

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 12 matching lines @@
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/frame/FrameView.h"
 
 #include "HTMLNames.h"
 #include "RuntimeEnabledFeatures.h"
 #include "core/accessibility/AXObjectCache.h"
+#include "core/animation/AnimationClock.h"
 #include "core/animation/DocumentTimeline.h"
 #include "core/css/FontFaceSet.h"
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/DocumentMarkerController.h"
 #include "core/editing/FrameSelection.h"
 #include "core/events/OverflowEvent.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/fetch/TextResourceDecoder.h"
 #include "core/html/HTMLFrameElement.h"
 #include "core/html/HTMLHtmlElement.h"
@@ skipping 1975 matching lines @@
     m_delayedLayout = false;
 }
 
 void FrameView::serviceScriptedAnimations(double monotonicAnimationStartTime)
 {
     for (RefPtr<Frame> frame = m_frame; frame; frame = frame->tree().traverseNext()) {
         frame->view()->serviceScrollAnimations();
         if (!RuntimeEnabledFeatures::webAnimationsCSSEnabled())
             frame->animation().serviceAnimations();
         if (RuntimeEnabledFeatures::webAnimationsEnabled()) {
-            frame->document()->timeline()->serviceAnimations(monotonicAnimationStartTime);
-            frame->document()->transitionTimeline()->serviceAnimations(monotonicAnimationStartTime);
+            frame->document()->animationClock().updateTime(monotonicAnimationStartTime);
+            bool didTriggerStyleRecalc = frame->document()->timeline()->serviceAnimations();

[dstockwell, 2013/11/05 05:05:44]

It's unfortunate that we have to thread this all the way out. Wouldn't it be
sufficient to test !(frame->document->needsStyleRecalc() ||
...->childNeedsStyleRecalc()) ?

+            didTriggerStyleRecalc |= frame->document()->transitionTimeline()->serviceAnimations();
+            if (!didTriggerStyleRecalc)
+                frame->document()->animationClock().unfreeze();
             frame->document()->timeline()->dispatchEvents();
             frame->document()->transitionTimeline()->dispatchEvents();
         }
     }
 
     Vector<RefPtr<Document> > documents;
     for (Frame* frame = m_frame.get(); frame; frame = frame->tree().traverseNext())
         documents.append(frame->document());
 
     for (size_t i = 0; i < documents.size(); ++i)
@@ skipping 1420 matching lines @@
 void FrameView::setLayoutSizeInternal(const IntSize& size)
 {
     if (m_layoutSize == size)
         return;
 
     m_layoutSize = size;
     contentsResized();
 }
 
 } // namespace WebCore