Add android bindings for PeerConnectionState.

This change makes it possible for android apps to use the new standards-compliant PeerConnectionState.

Bug: webrtc:9977
Change-Id: Iad19c38e664a59e86879715ec7a04a59a9894bee
Reviewed-on: https://webrtc-review.googlesource.com/c/109883
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25652}

examples/androidtests/src/org/appspot/apprtc/test/PeerConnectionClientTest.java

@@ -183,6 +183,16 @@ public class PeerConnectionClientTest implements PeerConnectionEvents {
     }
   }
 
+  @Override
+  public void onConnected() {
+    Log.d(TAG, "DTLS Connected");
+  }
+
+  @Override
+  public void onDisconnected() {
+    Log.d(TAG, "DTLS Disconnected");
+  }
+
   @Override
   public void onPeerConnectionClosed() {
     Log.d(TAG, "PeerConnection closed");