Update iOS AppRTCDemo to use level controller.

webrtc/examples/objc/AppRTCDemo/ARDAppClient+Internal.h

 /*
  *  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 27 matching lines @@
 @property(nonatomic, strong) NSString *roomId;
 @property(nonatomic, strong) NSString *clientId;
 @property(nonatomic, assign) BOOL isInitiator;
 @property(nonatomic, strong) NSMutableArray *iceServers;
 @property(nonatomic, strong) NSURL *webSocketURL;
 @property(nonatomic, strong) NSURL *webSocketRestURL;
 @property(nonatomic, readonly) BOOL isLoopback;
 @property(nonatomic, readonly) BOOL isAudioOnly;
 @property(nonatomic, readonly) BOOL shouldMakeAecDump;
 @property(nonatomic, assign) BOOL isAecDumpActive;
+@property(nonatomic, readonly) BOOL shouldUseLevelControl;
 
 @property(nonatomic, strong)
     RTCMediaConstraints *defaultPeerConnectionConstraints;
 
 - (instancetype)initWithRoomServerClient:(id<ARDRoomServerClient>)rsClient
                         signalingChannel:(id<ARDSignalingChannel>)channel
                               turnClient:(id<ARDTURNClient>)turnClient
                                 delegate:(id<ARDAppClientDelegate>)delegate;
 
 @end