function makeCell(connection) {
    const cell = new shaka.offline.indexeddb.V5StorageCell(
        connection,
        segmentStore,
        manifestStore);

    // Track the cell so that we can destroy it when the test is over.
    cells.push(cell);

    return cell;
  }
@param {IDBDatabase} connection
@return {shaka.extern.StorageCell}