void RenderFrameSet::layout()
{
    StackStats::LayoutCheckPoint layoutCheckPoint;
    ASSERT(needsLayout());

    bool doFullRepaint = selfNeedsLayout() && checkForRepaintDuringLayout();
    LayoutRect oldBounds;
    RenderLayerModelObject* repaintContainer = 0;
    if (doFullRepaint) {
        repaintContainer = containerForRepaint();
        oldBounds = clippedOverflowRectForRepaint(repaintContainer);
    }

    if (!parent()->isFrameSet() && !document().printing()) {
        setWidth(view().viewWidth());
        setHeight(view().viewHeight());
    }

    unsigned cols = frameSetElement().totalCols();
    unsigned rows = frameSetElement().totalRows();

    if (m_rows.m_sizes.size() != rows || m_cols.m_sizes.size() != cols) {
        m_rows.resize(rows);
        m_cols.resize(cols);
    }

    LayoutUnit borderThickness = frameSetElement().border();
    layOutAxis(m_rows, frameSetElement().rowLengths(), height() - (rows - 1) * borderThickness);
    layOutAxis(m_cols, frameSetElement().colLengths(), width() - (cols - 1) * borderThickness);

    if (flattenFrameSet())
        positionFramesWithFlattening();
    else
        positionFrames();

    RenderBox::layout();

    computeEdgeInfo();

    updateLayerTransform();

    if (doFullRepaint) {
        repaintUsingContainer(repaintContainer, pixelSnappedIntRect(oldBounds));
        LayoutRect newBounds = clippedOverflowRectForRepaint(repaintContainer);
        if (newBounds != oldBounds)
            repaintUsingContainer(repaintContainer, pixelSnappedIntRect(newBounds));
    }

    clearNeedsLayout();
}
void RenderLayerModelObject::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
{
    RenderElement::styleDidChange(diff, oldStyle);
    updateFromStyle();

    if (requiresLayer()) {
        if (!layer() && layerCreationAllowedForSubtree()) {
            if (s_wasFloating && isFloating())
                setChildNeedsLayout();
            createLayer();
            if (parent() && !needsLayout() && containingBlock()) {
                layer()->setRepaintStatus(NeedsFullRepaint);
                // There is only one layer to update, it is not worth using |cachedOffset| since
                // we are not sure the value will be used.
                layer()->updateLayerPositions(0);
            }
        }
    } else if (layer() && layer()->parent()) {
#if ENABLE(CSS_COMPOSITING)
        if (oldStyle->hasBlendMode())
            layer()->parent()->dirtyAncestorChainHasBlendingDescendants();
#endif
        setHasTransformRelatedProperty(false); // All transform-related propeties force layers, so we know we don't have one or the object doesn't support them.
        setHasReflection(false);
        // Repaint the about to be destroyed self-painting layer when style change also triggers repaint.
        if (layer()->isSelfPaintingLayer() && layer()->repaintStatus() == NeedsFullRepaint)
            repaintUsingContainer(containerForRepaint(), layer()->repaintRect());
        layer()->removeOnlyThisLayer(); // calls destroyLayer() which clears m_layer
        if (s_wasFloating && isFloating())
            setChildNeedsLayout();
        if (s_hadTransform)
            setNeedsLayoutAndPrefWidthsRecalc();
    }

    if (layer()) {
        layer()->styleChanged(diff, oldStyle);
        if (s_hadLayer && layer()->isSelfPaintingLayer() != s_layerWasSelfPainting)
            setChildNeedsLayout();
    }

    bool newStyleIsViewportConstrained = style().hasViewportConstrainedPosition();
    bool oldStyleIsViewportConstrained = oldStyle && oldStyle->hasViewportConstrainedPosition();
    if (newStyleIsViewportConstrained != oldStyleIsViewportConstrained) {
        if (newStyleIsViewportConstrained && layer())
            view().frameView().addViewportConstrainedObject(this);
        else
            view().frameView().removeViewportConstrainedObject(this);
    }

#if ENABLE(CSS_SCROLL_SNAP)
    const RenderStyle& newStyle = style();
    if (oldStyle && scrollSnapContainerRequiresUpdateForStyleUpdate(*oldStyle, newStyle)) {
        if (RenderLayer* renderLayer = layer()) {
            renderLayer->updateSnapOffsets();
            renderLayer->updateScrollSnapState();
        } else if (isBody() || isDocumentElementRenderer()) {
            FrameView& frameView = view().frameView();
            frameView.updateSnapOffsets();
            frameView.updateScrollSnapState();
            frameView.updateScrollingCoordinatorScrollSnapProperties();
        }
    }
    if (oldStyle && oldStyle->scrollSnapCoordinates() != newStyle.scrollSnapCoordinates()) {
        const RenderBox* scrollSnapBox = enclosingBox().findEnclosingScrollableContainer();
        if (scrollSnapBox && scrollSnapBox->layer()) {
            const RenderStyle& style = scrollSnapBox->style();
            if (style.scrollSnapType() != ScrollSnapType::None) {
                scrollSnapBox->layer()->updateSnapOffsets();
                scrollSnapBox->layer()->updateScrollSnapState();
                if (scrollSnapBox->isBody() || scrollSnapBox->isDocumentElementRenderer())
                    scrollSnapBox->view().frameView().updateScrollingCoordinatorScrollSnapProperties();
            }
        }
    }
#endif
}