Invalidate scrollbars when window activity changes if needed

third_party/WebKit/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 327 matching lines @@
 {
     bool usesWindowInactiveSelector = m_frame->document()->styleEngine().usesWindowInactiveSelector();
 
     const ChildrenWidgetSet* viewChildren = children();
     for (const RefPtrWillBeMember<Widget>& child : *viewChildren) {
         Widget* widget = child.get();
         if (widget->isFrameView())
             toFrameView(widget)->invalidateAllCustomScrollbarsOnActiveChanged();
         else if (usesWindowInactiveSelector && widget->isScrollbar() && toScrollbar(widget)->isCustomScrollbar())
             toScrollbar(widget)->styleChanged();
+        if (widget->isScrollbar())
+            toScrollbar(widget)->windowActiveChanged();
     }
     if (usesWindowInactiveSelector)
         recalculateCustomScrollbarStyle();
 }
 
 void FrameView::recalculateScrollbarOverlayStyle()
 {
     ScrollbarOverlayStyle oldOverlayStyle = scrollbarOverlayStyle();
     ScrollbarOverlayStyle overlayStyle = ScrollbarOverlayStyleDefault;
 
@@ skipping 3720 matching lines @@
 }
 
 bool FrameView::canThrottleRendering() const
 {
     if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
         return false;
     return m_hiddenForThrottling && m_crossOriginForThrottling;
 }
 
 } // namespace blink