Only scroll on main if the targeted frames need to scroll on main

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
index 01fcf7caf800c3006633f899fbc15749bb1896a5..7d0a445d4c49cfe9bc86cec82fa8d93f46933928 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
@@ -1714,8 +1714,8 @@ bool PaintLayerScrollableArea::usesCompositedScrolling() const {
 }
 
 bool PaintLayerScrollableArea::shouldScrollOnMainThread() const {
-  if (ScrollingCoordinator* scrollingCoordinator = getScrollingCoordinator()) {
-    if (scrollingCoordinator->shouldUpdateScrollLayerPositionOnMainThread())
+  if (LocalFrame* frame = box().frame()) {
+    if (frame->view()->mainThreadScrollingReasons())
       return true;
   }
   return ScrollableArea::shouldScrollOnMainThread();