[SPv2] Track paint offset change

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

 // Copyright 2014 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/ObjectPainter.h"
 
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutTheme.h"
@@ skipping 676 matching lines @@
   info.phase = PaintPhaseBlockBackground;
   m_layoutObject.paint(info, paintOffset);
   info.phase = PaintPhaseFloat;
   m_layoutObject.paint(info, paintOffset);
   info.phase = PaintPhaseForeground;
   m_layoutObject.paint(info, paintOffset);
   info.phase = PaintPhaseOutline;
   m_layoutObject.paint(info, paintOffset);
 }
 
+#if DCHECK_IS_ON()
+void ObjectPainter::doCheckPaintOffset(const PaintInfo& paintInfo,
+                                       const LayoutPoint& paintOffset) {
+  DCHECK(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+
+  // TODO(pdr): Let painter and paint property tree builder generate the same
+  // paint offset for LayoutScrollbarPart. crbug.com/664249.
+  if (m_layoutObject.isLayoutScrollbarPart())
+    return;
+
+  LayoutPoint adjustedPaintOffset = paintOffset;
+  if (m_layoutObject.isBox())
+    adjustedPaintOffset += toLayoutBox(m_layoutObject).location();
+  DCHECK(m_layoutObject.previousPaintOffset() == adjustedPaintOffset);
+}
+#endif
+
 }  // namespace blink