Update Unit test for AppRTCMobile app

webrtc/examples/objc/AppRTCMobile/ARDAppClient.m

 /*
  *  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 299 matching lines @@
   _isInitiator = NO;
   _hasReceivedSdp = NO;
   _messageQueue = [NSMutableArray array];
 #if defined(WEBRTC_IOS)
   [_factory stopAecDump];
   [_peerConnection stopRtcEventLog];
 #endif
   _peerConnection = nil;
   self.state = kARDAppClientStateDisconnected;
 #if defined(WEBRTC_IOS)
-  RTCStopInternalCapture();
+  if (kARDAppClientEnableTracing) {
+    RTCStopInternalCapture();
+  }
 #endif
 }
 
 #pragma mark - ARDSignalingChannelDelegate
 
 - (void)channel:(id<ARDSignalingChannel>)channel
     didReceiveMessage:(ARDSignalingMessage *)message {
   switch (message.type) {
     case kARDSignalingMessageTypeOffer:
     case kARDSignalingMessageTypeAnswer:
@@ skipping 506 matching lines @@
                                          code:kARDAppClientErrorInvalidRoom
                                      userInfo:@{
         NSLocalizedDescriptionKey: @"Invalid room.",
       }];
       break;
   }
   return error;
 }
 
 @end