Move sticky position constraints update to the pre-paint tree walk.

third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/compositing/CompositingInputsUpdater.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBlock.h"
@@ skipping 84 matching lines @@
 void CompositingInputsUpdater::updateRecursive(PaintLayer* layer,
                                                UpdateType updateType,
                                                AncestorInfo info) {
   if (!layer->childNeedsCompositingInputsUpdate() && updateType != ForceUpdate)
     return;
 
   const PaintLayer* previousOverflowLayer = layer->ancestorOverflowLayer();
   layer->updateAncestorOverflowLayer(info.lastOverflowClipLayer);
   if (info.lastOverflowClipLayer && layer->needsCompositingInputsUpdate() &&
       layer->layoutObject()->style()->position() == StickyPosition) {
-    if (info.lastOverflowClipLayer != previousOverflowLayer) {
+    if (info.lastOverflowClipLayer != previousOverflowLayer &&
+        !RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
       // Old ancestor scroller should no longer have these constraints.
       ASSERT(!previousOverflowLayer ||
              !previousOverflowLayer->getScrollableArea()
                   ->stickyConstraintsMap()
                   .contains(layer));
 
       if (info.lastOverflowClipLayer->isRootLayer())
         layer->layoutObject()
             ->view()
             ->frameView()
@@ skipping 140 matching lines @@
   ASSERT(!layer->needsCompositingInputsUpdate());
 
   for (PaintLayer* child = layer->firstChild(); child;
        child = child->nextSibling())
     assertNeedsCompositingInputsUpdateBitsCleared(child);
 }
 
 #endif
 
 }  // namespace blink