 = subHist.unit;
        } else if (unit !== subHist.unit) {
          // The subrows have different units, so the overview chart cannot
          // use a single unit to format all of the values, so don't display
          // an overview chart at all.
          data.splice(0);
          break;
        }

        const refHist = subRow.columns.get(referenceDisplayLabel);
        const statName = subHist.getAvailableStatisticName(
            displayStatisticName, refHist);
        const statScalar = subHist