datastore: Update AllocateIDs to take keys.

filter/txnBuf/ds_txn.go

Index: filter/txnBuf/ds_txn.go
diff --git a/filter/txnBuf/ds_txn.go b/filter/txnBuf/ds_txn.go
index bc72eae5d374fd8ab089d53cebfecefe825ddc53..1521f415d8be689a3f142e269216c48273af817a 100644
--- a/filter/txnBuf/ds_txn.go
+++ b/filter/txnBuf/ds_txn.go
@@ -32,8 +32,8 @@ func (d *dsTxnBuf) DecodeCursor(s string) (ds.Cursor, error) {
 	return d.state.parentDS.DecodeCursor(s)
 }
 
-func (d *dsTxnBuf) AllocateIDs(incomplete *ds.Key, n int) (start int64, err error) {
-	return d.state.parentDS.AllocateIDs(incomplete, n)
+func (d *dsTxnBuf) AllocateIDs(keys []*ds.Key) error {
+	return d.state.parentDS.AllocateIDs(keys)
 }
 
 func (d *dsTxnBuf) GetMulti(keys []*ds.Key, metas ds.MultiMetaGetter, cb ds.GetMultiCB) error {