mempool: refactor fetchInputUtxosFromUData to fetchInputUtxosFromLeaves

Since the leaves are the actual data we need, it's better that the
function argument is the leaves and not the udata. This allows for
calling fetchInputUtxosFromLeaves from a different mempool method as
the leaves are kept track of.

mempool/mempool.go

@@ -826,18 +826,18 @@ func (mp *TxPool) fetchInputUtxos(tx *btcutil.Tx) (*blockchain.UtxoViewpoint, er
 	return utxoView, nil
 }
 
-// fetchInputUtxosFromUData extracts utxo details about the input transactions
-// provided in the UData for the passed transaction.  First, it extracts the
+// fetchInputUtxosFromLeaves extracts utxo details about the input transactions
+// provided in the leaves for the passed transaction.  First, it extracts the
 // details from the udata, then it adjusts them based upon the contents of the
 // transaction pool.
 //
 // This function MUST be called with the mempool lock held (for reads).
-func (mp *TxPool) fetchInputUtxosFromUData(tx *btcutil.Tx, ud *wire.UData) *blockchain.UtxoViewpoint {
+func (mp *TxPool) fetchInputUtxosFromLeaves(tx *btcutil.Tx, leaves []wire.LeafData) *blockchain.UtxoViewpoint {
 	utxoView := blockchain.NewUtxoViewpoint()
 	viewEntries := utxoView.Entries()
 
 	// Loop through leaf datas and convert them into UtxoEntries.
-	for _, ld := range ud.LeafDatas {
+	for _, ld := range leaves {
 		// If the leaf data was marked to be unconfirmed, set as nil.
 		// The outpoint for the txIn that this LeafData is supposed to
 		// represent will be attempted to be fetched from the mempool
@@ -1492,7 +1492,7 @@ func (mp *TxPool) checkMempoolAcceptance(tx *btcutil.Tx,
 		log.Debugf("VerifyUData passed for tx %s", txHash.String())
 
 		// After the validation passes, turn that proof into a utxoView.
-		utxoView = mp.fetchInputUtxosFromUData(tx, ud)
+		utxoView = mp.fetchInputUtxosFromLeaves(tx, ud.LeafDatas)
 	} else {
 		// Fetch all of the unspent transaction outputs referenced by the
 		// inputs to this transaction. This function also attempts to fetch the