Add stats overlay to iOS AppRTCDemo.

webrtc/examples/objc/AppRTCDemo/mac/APPRTCViewController.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 252 matching lines @@
   _remoteVideoTrack = remoteVideoTrack;
   [_remoteVideoTrack addRenderer:self.mainView.remoteVideoView];
 }
 
 - (void)appClient:(ARDAppClient *)client
          didError:(NSError *)error {
   [self showAlertWithMessage:[NSString stringWithFormat:@"%@", error]];
   [self disconnect];
 }
 
+- (void)appClient:(ARDAppClient *)client
+      didGetStats:(NSArray *)stats {
+}
+
 #pragma mark - APPRTCMainViewDelegate
 
 - (void)appRTCMainView:(APPRTCMainView*)mainView
         didEnterRoomId:(NSString*)roomId {
   [_client disconnect];
   ARDAppClient *client = [[ARDAppClient alloc] initWithDelegate:self];
   [client connectToRoomWithId:roomId options:nil];
   _client = client;
 }
 
@@ skipping 14 matching lines @@
   _remoteVideoTrack = nil;
   [self.mainView.remoteVideoView renderFrame:nil];
 }
 
 - (void)disconnect {
   [self resetUI];
   [_client disconnect];
 }
 
 @end