Always call UpdateCompositedScrollOffset, not just for the root layer

Bug: 927560
Change-Id: I1d5522aae4f11dd3f5b8947bb089bac1bf19bdb4
Reviewed-on: https://chromium-review.googlesource.com/c/1452701
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Mason Freed <masonfreed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628942}
PaintLayerScrollableArea::ConvertFromScrollbarToContainingEmbeddedContentView(
    const Scrollbar& scrollbar,
    const IntRect& scrollbar_rect) const {
  LayoutView* view = GetLayoutBox()->View();
  if (!view)
    return scrollbar_rect;

  IntRect rect = scrollbar_rect;
  rect.Move(ScrollbarOffset(scrollbar));

  return view->GetFrameView()->ConvertFromLayoutObject(*GetLayoutBox(), rect);
}

PaintLayerScrollableArea::ConvertFromScrollbarToContainingEmbeddedContentView(
    const Scrollbar& scrollbar,
    const IntRect& scrollbar_rect) const {
  LayoutView* view = GetLayoutBox()->View();
  if (!view)
    return scrollbar_rect;

  IntRect rect = scrollbar_rect;
  rect.Move(ScrollbarOffset(scrollbar));

  return view->GetFrameView()->ConvertFromLayoutObject(*GetLayoutBox(), rect);
}
