Fix under-invalidation about view background change caused by body style change

Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 3175 matching lines @@
 }
 
 void LayoutObject::setShouldInvalidateSelection()
 {
     if (!canUpdateSelectionOnRootLineBoxes())
         return;
 
     m_bitfields.setShouldInvalidateSelection(true);
     markContainerChainForPaintInvalidation();
 }
+
 void LayoutObject::setShouldDoFullPaintInvalidation(PaintInvalidationReason reason)
 {
     // Only full invalidation reasons are allowed.
     ASSERT(isFullPaintInvalidationReason(reason));
 
     if (m_bitfields.fullPaintInvalidationReason() == PaintInvalidationNone) {
         if (reason == PaintInvalidationFull)
             reason = documentLifecycleBasedPaintInvalidationReason(document().lifecycle());
         m_bitfields.setFullPaintInvalidationReason(reason);
+
+        if (RuntimeEnabledFeatures::slimmingPaintEnabled() && isBody()) {
+            // The rootObject paints view's background. We need to invalidate it when
+            // view's background changes because of change of body's style.
+            // FIXME: The condition is broader than needed for simplicity.
+            // Might remove this when fixing crbug.com/475115.
+            if (LayoutObject* rootObject = document().documentElement()->layoutObject())
+                rootObject->setShouldDoFullPaintInvalidation();
+        }
     }
 
     ASSERT(document().lifecycle().state() != DocumentLifecycle::InPaintInvalidation);
     frame()->page()->animator().scheduleVisualUpdate(); // In case that this is called outside of FrameView::updateLayoutAndStyleForPainting().
     markContainerChainForPaintInvalidation();
 }
 
 void LayoutObject::setMayNeedPaintInvalidation()
 {
     if (mayNeedPaintInvalidation())
@@ skipping 92 matching lines @@
 {
     if (object1) {
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif