iOS AppRTC: First unit test.

Tests basic session ICE connection by stubbing out network components, which have been refactored to faciliate testing.

BUG=3994
R=jiayl@webrtc.org, kjellander@webrtc.org, phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/28349004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@8002 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/examples/objc/AppRTCDemo/mac/APPRTCViewController.m

@@ -266,6 +266,10 @@ static NSUInteger const kLogViewHeight = 280;
   }
 }
 
+- (void)appClient:(ARDAppClient *)client
+    didChangeConnectionState:(RTCICEConnectionState)state {
+}
+
 - (void)appClient:(ARDAppClient *)client
     didReceiveLocalVideoTrack:(RTCVideoTrack *)localVideoTrack {
   _localVideoTrack = localVideoTrack;