Account for non-composited scroll offset of scrollbars.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintInvalidationCapableScrollableArea.h"
 
 #include "core/frame/Settings.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutScrollbar.h"
@@ skipping 20 matching lines @@
 
 static LayoutRect scrollControlPaintInvalidationRect(
     const IntRect& scrollControlRect,
     const LayoutBox& box,
     const PaintInvalidatorContext& context) {
   LayoutRect paintInvalidationRect(scrollControlRect);
   // No need to apply any paint offset. Scroll controls paint in a different
   // transform space than their contained box (the scrollbarPaintOffset
   // transform node).
   if (!paintInvalidationRect.isEmpty() &&
-      !RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+      !RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     context.mapLocalRectToPaintInvalidationBacking(box, paintInvalidationRect);
+
+    IntSize adjustment = box.scrollAdjustmentForPaintInvalidation(
+        *context.paintInvalidationContainer);
+    paintInvalidationRect.move(adjustment);
+  }
   return paintInvalidationRect;
 }
 
 // Returns true if the scroll control is invalidated.
 static bool invalidatePaintOfScrollControlIfNeeded(
     const LayoutRect& newPaintInvalidationRect,
     const LayoutRect& previousPaintInvalidationRect,
     bool needsPaintInvalidation,
     LayoutBox& box,
     const LayoutBoxModelObject& paintInvalidationContainer) {
@@ skipping 145 matching lines @@
   fullBounds.unite(m_scrollCornerAndResizerPreviousPaintInvalidationRect);
   return fullBounds;
 }
 
 void PaintInvalidationCapableScrollableArea::
     scrollControlWasSetNeedsPaintInvalidation() {
   layoutBox()->setMayNeedPaintInvalidation();
 }
 
 }  // namespace blink