[RootLayerScrolls] Fix frame scrolling layer in ScrollingCoordinator

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights
  * reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@gmail.com>
@@ skipping 547 matching lines @@
 }
 
 int PaintLayerScrollableArea::visibleWidth() const {
   return layer()->size().width();
 }
 
 IntSize PaintLayerScrollableArea::contentsSize() const {
   return IntSize(pixelSnappedScrollWidth(), pixelSnappedScrollHeight());
 }
 
+bool PaintLayerScrollableArea::isScrollable() const {
+  return scrollsOverflow();
+}
+
 IntPoint PaintLayerScrollableArea::lastKnownMousePosition() const {
   return box().frame() ? box().frame()->eventHandler().lastKnownMousePosition()
                        : IntPoint();
 }
 
 bool PaintLayerScrollableArea::scrollAnimatorEnabled() const {
   if (Settings* settings = box().frame()->settings())
     return settings->getScrollAnimatorEnabled();
   return false;
 }
@@ skipping 1531 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollOffsetClampScope::
     clampScrollableAreas() {
   for (auto& scrollableArea : *s_needsClamp)
     scrollableArea->clampScrollOffsetAfterOverflowChange();
   delete s_needsClamp;
   s_needsClamp = nullptr;
 }
 
 }  // namespace blink