removeSourceTiles(tile) {
    const tileKey = tile.getKey();
    const sourceTiles = tile.sourceTiles;
    for (let i = 0, ii = sourceTiles.length; i < ii; ++i) {
      const sourceTileUrl = sourceTiles[i].getTileUrl();
      if (!this.tileKeysBySourceTileUrl_[sourceTileUrl]) {
        return;
      }
      const index =
        this.tileKeysBySourceTileUrl_[sourceTileUrl].indexOf(tileKey);
      if (index === -1) {
        continue;
      }
      this.tileKeysBySourceTileUrl_[sourceTileUrl].splice(index, 1);
      if (this.tileKeysBySourceTileUrl_[sourceTileUrl].length === 0) {
        delete this.tileKeysBySourceTileUrl_[sourceTileUrl];
        delete this.sourceTiles_[sourceTileUrl];
      }
    }
  }
@param {VectorRenderTile} tile Vector render tile.