Update reason after full paint invalidation

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

 // Copyright 2016 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/ObjectPaintInvalidator.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/api/LayoutPartItem.h"
@@ skipping 619 matching lines @@
           (m_context.forcedSubtreeInvalidationFlags &
            PaintInvalidatorContext::ForcedSubtreeSVGResourceChange)) {
         reason = PaintInvalidationSVGResourceChange;
         break;
       }
       return PaintInvalidationNone;
     case PaintInvalidationDelayedFull:
       return PaintInvalidationDelayedFull;
     default:
       DCHECK(isImmediateFullPaintInvalidationReason(reason));
+      // This allows descendants to know the computed reason if it's different
+      // from the original reason before paint invalidation.
+      m_object.getMutableForPainting().setShouldDoFullPaintInvalidation(reason);
       fullyInvalidatePaint(reason, m_context.oldVisualRect,
                            m_object.visualRect());
   }
 
   m_context.paintingLayer->setNeedsRepaint();
   m_object.invalidateDisplayItemClients(reason);
   return reason;
 }
 
 DisablePaintInvalidationStateAsserts::DisablePaintInvalidationStateAsserts()
     : m_disabler(&gDisablePaintInvalidationStateAsserts, true) {}
 
 }  // namespace blink