Remove userId and userName from rtpconn.

They're redundant with the client field.

rtpconn/rtpconn.go

@@ -508,8 +508,6 @@ type rtpUpConnection struct {
 	id            string
 	client        group.Client
 	label         string
-	userId        string
-	username      string
 	pc            *webrtc.PeerConnection
 	iceCandidates []*webrtc.ICECandidateInit
 
@@ -548,7 +546,7 @@ func (up *rtpUpConnection) Label() string {
 }
 
 func (up *rtpUpConnection) User() (string, string) {
-	return up.userId, up.username
+	return up.client.Id(), up.client.Username()
 }
 
 func (up *rtpUpConnection) AddLocal(local conn.Down) error {

rtpconn/webclient.go

@@ -211,9 +211,12 @@ func delUpConn(c *webClient, id string, userId string, push bool) error {
 		c.mu.Unlock()
 		return os.ErrNotExist
 	}
-	if userId != "" && conn.userId != userId {
-		c.mu.Unlock()
-		return ErrUserMismatch
+	if userId != "" {
+		id, _ := conn.User()
+		if id != userId {
+			c.mu.Unlock()
+			return ErrUserMismatch
+		}
 	}
 
 	replace := conn.getReplace(false)
@@ -576,8 +579,6 @@ func gotOffer(c *webClient, id, label string, sdp string, replace string) error
 		return err
 	}
 
-	up.userId = c.Id()
-	up.username = c.Username()
 	if replace != "" {
 		up.replace = replace
 		delUpConn(c, replace, c.Id(), false)