Revert of Adding "first packet received" notification to PeerConnectionObserver.

talk/app/webrtc/objc/RTCPeerConnectionObserver.mm

Index: talk/app/webrtc/objc/RTCPeerConnectionObserver.mm
diff --git a/talk/app/webrtc/objc/RTCPeerConnectionObserver.mm b/talk/app/webrtc/objc/RTCPeerConnectionObserver.mm
index 47246cbef7040c0e46b2fdcf1c60f598d018bc22..411cd6cb899a9a9ba33041884ff33a49b3a3c8c0 100644
--- a/talk/app/webrtc/objc/RTCPeerConnectionObserver.mm
+++ b/talk/app/webrtc/objc/RTCPeerConnectionObserver.mm
@@ -105,9 +105,4 @@
                            gotICECandidate:iceCandidate];
 }
 
-void RTCPeerConnectionObserver::OnFirstMediaPacketReceived() {
-  id<RTCPeerConnectionDelegate> delegate = _peerConnection.delegate;
-  [delegate peerConnectionOnFirstMediaPacketReceived:_peerConnection];
-}
-
 }  // namespace webrtc