Updating custom scrollbar style

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 305 matching lines @@
     Scrollbar* verticalBar = verticalScrollbar();
     if (verticalBar && verticalBar->isCustomScrollbar())
         setHasVerticalScrollbar(false);
 
     if (m_scrollCorner) {
         m_scrollCorner->destroy();
         m_scrollCorner = nullptr;
     }
 }
 
+void FrameView::recalculateCustomScrollbarStyle()
+{
+    bool didStyleChange = false;
+    if (m_horizontalScrollbar && m_horizontalScrollbar->isCustomScrollbar()) {
+        m_horizontalScrollbar->styleChanged();
+        didStyleChange = true;
+    }
+    if (m_verticalScrollbar && m_verticalScrollbar->isCustomScrollbar()) {
+        m_verticalScrollbar->styleChanged();
+        didStyleChange = true;
+    }
+    if (didStyleChange) {
+        updateScrollbarGeometry();
+        updateScrollCorner();
+        positionScrollbarLayers();
+    }
+}
+
 void FrameView::recalculateScrollbarOverlayStyle()
 {
     ScrollbarOverlayStyle oldOverlayStyle = scrollbarOverlayStyle();
     ScrollbarOverlayStyle overlayStyle = ScrollbarOverlayStyleDefault;
 
     Color backgroundColor = documentBackgroundColor();
     // Reduce the background color from RGB to a lightness value
     // and determine which scrollbar style to use based on a lightness
     // heuristic.
     double hue, saturation, lightness;
@@ skipping 3598 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink