Hide and delete no longer needed public methods

Although the rest of the methods are no longer needed since the handling
of WebRTC messages was moved to PeerConnectionWrapper "setSessionId()"
was not needed even before that.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

app/src/main/java/com/nextcloud/talk/webrtc/PeerConnectionWrapper.java

@@ -169,7 +169,7 @@ public class PeerConnectionWrapper {
         }
     }
 
-    public void drainIceCandidates() {
+    private void drainIceCandidates() {
 
         if (peerConnection != null) {
             for (IceCandidate iceCandidate : iceCandidates) {
@@ -180,11 +180,7 @@ public class PeerConnectionWrapper {
         }
     }
 
-    public MagicSdpObserver getMagicSdpObserver() {
-        return magicSdpObserver;
-    }
-
-    public void addCandidate(IceCandidate iceCandidate) {
+    private void addCandidate(IceCandidate iceCandidate) {
         if (peerConnection != null && peerConnection.getRemoteDescription() != null) {
             peerConnection.addIceCandidate(iceCandidate);
         } else {
@@ -224,10 +220,6 @@ public class PeerConnectionWrapper {
         return sessionId;
     }
 
-    public void setSessionId(String sessionId) {
-        this.sessionId = sessionId;
-    }
-
     public String getNick() {
         if (!TextUtils.isEmpty(nick)) {
             return nick;
@@ -236,7 +228,7 @@ public class PeerConnectionWrapper {
         }
     }
 
-    public void setNick(String nick) {
+    private void setNick(String nick) {
         this.nick = nick;
     }