Created a java wrapper for the callback OnAddTrack to PeerConnection.Observer

webrtc/sdk/android/api/org/webrtc/PeerConnection.java

Index: webrtc/sdk/android/api/org/webrtc/PeerConnection.java
diff --git a/webrtc/sdk/android/api/org/webrtc/PeerConnection.java b/webrtc/sdk/android/api/org/webrtc/PeerConnection.java
index ab085985195acf34f0c96ab9c4e769d2dfecee1b..b4ad5795fe04c2c34c9a7890d597220e4c4fd5ba 100644
--- a/webrtc/sdk/android/api/org/webrtc/PeerConnection.java
+++ b/webrtc/sdk/android/api/org/webrtc/PeerConnection.java
@@ -80,6 +80,12 @@ public class PeerConnection {
 
     /** Triggered when renegotiation is necessary. */
     public void onRenegotiationNeeded();
+
+    /**
+     * Triggered when a new track is signaled by the remote peer, as a result of
+     * setRemoteDescription.
+     */
+    public void onAddTrack(RtpReceiver receiver, MediaStream[] mediaStreams);
   }
 
   /** Java version of PeerConnectionInterface.IceServer. */