Adding "first packet received" notification to PeerConnectionObserver.

webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java

 /*
  *  Copyright 2014 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 983 matching lines @@
     public void onDataChannel(final DataChannel dc) {
       reportError("AppRTC doesn't use data channels, but got: " + dc.label()
           + " anyway!");
     }
 
     @Override
     public void onRenegotiationNeeded() {
       // No need to do anything; AppRTC follows a pre-agreed-upon
       // signaling/negotiation protocol.
     }
+
+    @Override
+    public void onFirstMediaPacketReceived() {
+    }
   }
 
   // Implementation detail: handle offer creation/signaling and answer setting,
   // as well as adding remote ICE candidates once the answer SDP is set.
   private class SDPObserver implements SdpObserver {
     @Override
     public void onCreateSuccess(final SessionDescription origSdp) {
       if (localSdp != null) {
         reportError("Multiple SDP create.");
         return;
@@ skipping 63 matching lines @@
     public void onCreateFailure(final String error) {
       reportError("createSDP error: " + error);
     }
 
     @Override
     public void onSetFailure(final String error) {
       reportError("setSDP error: " + error);
     }
   }
 }