Revert changes is the use of CompositingReasonOutOfFlowClipping

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

Index: third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
index 2924e5944e56d5997a4bf87d88cf8cb4b910d2b1..732e0b5ef280411f629f107826dcebad146b07ba 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
@@ -143,8 +143,17 @@ CompositingReasons CompositingReasonFinder::nonStyleDeterminedDirectReasons(
   CompositingReasons directReasons = CompositingReasonNone;
   LayoutObject* layoutObject = layer->layoutObject();
 
-  if (layer->needsCompositedScrolling())
+  bool checkForClipParent =
+      (m_compositingTriggers & OverflowScrollTrigger) &&
+      layer->ancestorScrollingLayer() &&
+      layer->ancestorScrollingLayer()->compositingState() ==
+          PaintsIntoOwnBacking;
+  if (layer->needsCompositedScrolling()) {
+    checkForClipParent = true;
     directReasons |= CompositingReasonOverflowScrollingTouch;
+  }
+  if (checkForClipParent && layer->clipParent())
+    directReasons |= CompositingReasonOutOfFlowClipping;
 
   // Composite |layer| if it is inside of an ancestor scrolling layer, but that
   // scrolling layer is not on the stacking context ancestor chain of |layer|.