void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTreeBuilderContext& context)
{
    PaintPropertyTreeBuilderContext localContext(context);

    deriveBorderBoxFromContainerContext(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForPaintOffsetTranslation = createPaintOffsetTranslationIfNeeded(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = createTransformIfNeeded(object, localContext);
    RefPtr<EffectPaintPropertyNode> newEffectNode = createEffectIfNeeded(object, localContext);
    RefPtr<ClipPaintPropertyNode> newClipNodeForOverflowClip = createOverflowClipIfNeeded(object, localContext);
    // TODO(trchen): Insert flattening transform here, as specified by
    // http://www.w3.org/TR/css3-transforms/#transform-style-property
    RefPtr<TransformPaintPropertyNode> newTransformNodeForPerspective = createPerspectiveIfNeeded(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollTranslation = createScrollTranslationIfNeeded(object, localContext);
    updateOutOfFlowContext(object, newTransformNodeForTransform, localContext);

    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForScrollTranslation) {
        OwnPtr<ObjectPaintProperties> updatedPaintProperties = ObjectPaintProperties::create(
            newTransformNodeForPaintOffsetTranslation.release(),
            newTransformNodeForTransform.release(),
            newEffectNode.release(),
            newClipNodeForOverflowClip.release(),
            newTransformNodeForPerspective.release(),
            newTransformNodeForScrollTranslation.release());
        object.setObjectPaintProperties(updatedPaintProperties.release());
    } else {
        object.clearObjectPaintProperties();
    }

    for (LayoutObject* child = object.slowFirstChild(); child; child = child->nextSibling()) {
        if (child->isBoxModelObject() || child->isSVG())
            walk(*child, localContext);
    }
}
void PaintPropertyTreeBuilder::walk(LayoutBoxModelObject& object, const PaintPropertyTreeBuilderContext& context)
{
    ASSERT(object.isBox() != object.isLayoutInline()); // Either or.

    PaintPropertyTreeBuilderContext localContext(context);

    deriveBorderBoxFromContainerContext(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForPaintOffsetTranslation = createPaintOffsetTranslationIfNeeded(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = createTransformIfNeeded(object, localContext);
    RefPtr<EffectPaintPropertyNode> newEffectNode = createEffectIfNeeded(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForPerspective = createPerspectiveIfNeeded(object, localContext);
    RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollTranslation = createScrollTranslationIfNeeded(object, localContext);
    updateOutOfFlowContext(object, localContext);

    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newTransformNodeForPerspective || newTransformNodeForScrollTranslation) {
        OwnPtr<ObjectPaintProperties> updatedPaintProperties = ObjectPaintProperties::create(
            newTransformNodeForPaintOffsetTranslation.release(),
            newTransformNodeForTransform.release(),
            newEffectNode.release(),
            newTransformNodeForPerspective.release(),
            newTransformNodeForScrollTranslation.release());
        object.setObjectPaintProperties(updatedPaintProperties.release());
    } else {
        object.clearObjectPaintProperties();
    }

    // TODO(trchen): Walk subframes for LayoutFrame.

    // TODO(trchen): Implement SVG walk.
    if (object.isSVGRoot()) {
        return;
    }

    for (LayoutObject* child = object.slowFirstChild(); child; child = child->nextSibling()) {
        if (child->isText())
            continue;
        walk(toLayoutBoxModelObject(*child), localContext);
    }
}