Calculate paint invalidation rect for scrollbars

third_party/WebKit/Source/core/layout/LayoutView.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 437 matching lines @@
 
     ASSERT(paintInvalidationContainer);
     if (paintInvalidationContainer == this)
         return;
 
     Element* owner = document().ownerElement();
     if (!owner)
         return;
 
     if (LayoutBox* obj = owner->layoutBox()) {
-        // Intersect the viewport with the paint invalidation rect.
-        LayoutRect viewRectangle = viewRect();
-        rect.intersect(viewRectangle);
+        if (!state || !state->viewClippingAndScrollOffsetDisabled()) {
+            // Intersect the viewport with the paint invalidation rect.
+            LayoutRect viewRectangle = viewRect();
+            rect.intersect(viewRectangle);
 
-        // Adjust for scroll offset of the view.
-        rect.moveBy(-viewRectangle.location());
+            // Adjust for scroll offset of the view.
+            rect.moveBy(-viewRectangle.location());
+        }
 
         // Adjust for frame border.
         rect.move(obj->contentBoxOffset());
         obj->mapRectToPaintInvalidationBacking(paintInvalidationContainer, rect, 0);
     }
 }
 
 void LayoutView::adjustViewportConstrainedOffset(LayoutRect& rect, ViewportConstrainedPosition viewportConstraint) const
 {
     if (viewportConstraint != IsFixedPosition)
@@ skipping 489 matching lines @@
 }
 
 void LayoutView::sendMediaPositionChangeNotifications(const IntRect& visibleRect)
 {
     for (auto& media : m_mediaForPositionNotification) {
         media->notifyPositionMayHaveChanged(visibleRect);
     }
 }
 
 } // namespace blink