Invalidate paint properties on paint offset changes

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.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/PaintPropertyTreeBuilder.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
@@ skipping 778 matching lines @@
   context.transform = properties->propertyTreeState.transform();
   context.paintOffset = properties->paintOffset;
   context.shouldFlattenInheritedTransform =
       context.transform && context.transform->flattensInheritedTransform();
   context.renderingContextID =
       context.transform ? context.transform->renderingContextID() : 0;
   context.clip = properties->propertyTreeState.clip();
   context.scroll = properties->propertyTreeState.scroll();
 }
 
-static void deriveBorderBoxFromContainerContext(
+void PaintPropertyTreeBuilder::updateContextForBoxPosition(
     const LayoutObject& object,
     PaintPropertyTreeBuilderContext& context) {
   if (!object.isBoxModelObject())
     return;
 
   const LayoutBoxModelObject& boxModelObject = toLayoutBoxModelObject(object);
-
   switch (object.styleRef().position()) {
     case StaticPosition:
       break;
     case RelativePosition:
       context.current.paintOffset += boxModelObject.offsetForInFlowPosition();
       break;
     case AbsolutePosition: {
       if (context.isUnderMultiColumnSpanner) {
         const LayoutObject* container = boxModelObject.container();
         if (container != context.containerForAbsolutePosition) {
@@ skipping 65 matching lines @@
 void PaintPropertyTreeBuilder::updatePropertiesForSelf(
     const LayoutObject& object,
     PaintPropertyTreeBuilderContext& context) {
   if (!object.isBoxModelObject() && !object.isSVG())
     return;
 
 #if DCHECK_IS_ON()
   FindObjectPropertiesNeedingUpdateScope checkNeedsUpdateScope(object, context);
 #endif
 
-  deriveBorderBoxFromContainerContext(object, context);
-
   updatePaintOffsetTranslation(object, context);
   updateTransform(object, context);
   updateEffect(object, context);
   updateCssClip(object, context);
   updateLocalBorderBoxContext(object, context);
   updateScrollbarPaintOffset(object, context);
 }
 
 void PaintPropertyTreeBuilder::updatePropertiesForChildren(
     const LayoutObject& object,
     PaintPropertyTreeBuilderContext& context) {
   if (!object.isBoxModelObject() && !object.isSVG())
     return;
 
 #if DCHECK_IS_ON()
   FindObjectPropertiesNeedingUpdateScope checkNeedsUpdateScope(object, context);
 #endif
 
   updateOverflowClip(object, context);
   updatePerspective(object, context);
   updateSvgLocalToBorderBoxTransform(object, context);
   updateScrollAndScrollTranslation(object, context);
   updateOutOfFlowContext(object, context);
 }
 
 }  // namespace blink