/**
 * Hidden helper mounted once per grid (inside `<GridRoot>`) that publishes the measured `+N`
 * overflow chip widths and row gap to `apiRef.caches.multiSelect`. The measured chip comes from
 * the grid-level `baseChip` slot and the shared chip-row styling, so the metrics are identical
 * for every multiSelect column — one measurement per grid is enough. Renders nothing when the
 * grid has no multiSelect column. `ResizeObserver` re-fires when font / chip styles shift; the
 * cache dedupes equal metrics so subscribed cells only re-render on real change.
 */
export declare function GridMultiSelectMeasurer(): import("react/jsx-runtime").JSX.Element | null;