routing+discovery: extend ChannelGraphSource with zombie index methods

routing/router.go

@@ -89,6 +89,10 @@ type ChannelGraphSource interface {
 	IsStaleEdgePolicy(chanID lnwire.ShortChannelID, timestamp time.Time,
 		flags lnwire.ChanUpdateChanFlags) bool
 
+	// MarkEdgeLive clears an edge from our zombie index, deeming it as
+	// live.
+	MarkEdgeLive(chanID lnwire.ShortChannelID) error
+
 	// ForAllOutgoingChannels is used to iterate over all channels
 	// emanating from the "source" node which is the center of the
 	// star-graph.
@@ -2314,3 +2318,10 @@ func (r *ChannelRouter) IsStaleEdgePolicy(chanID lnwire.ShortChannelID,
 
 	return false
 }
+
+// MarkEdgeLive clears an edge from our zombie index, deeming it as live.
+//
+// NOTE: This method is part of the ChannelGraphSource interface.
+func (r *ChannelRouter) MarkEdgeLive(chanID lnwire.ShortChannelID) error {
+	return r.cfg.Graph.MarkEdgeLive(chanID.ToUint64())
+}