Add setting to AppRTCMobile for iOS, that can change capture resolution.

webrtc/examples/objc/AppRTCMobile/ARDAppClient.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.
  */
 
 #import <Foundation/Foundation.h>
 
 #import "WebRTC/RTCPeerConnection.h"
 #import "WebRTC/RTCVideoTrack.h"
 
 typedef NS_ENUM(NSInteger, ARDAppClientState) {
   // Disconnected from servers.
   kARDAppClientStateDisconnected,
   // Connecting to servers.
   kARDAppClientStateConnecting,
   // Connected to servers.
   kARDAppClientStateConnected,
 };
 
 @class ARDAppClient;
+@class RTCMediaConstraints;
+
 // The delegate is informed of pertinent events and will be called on the
 // main queue.
 @protocol ARDAppClientDelegate <NSObject>
 
 - (void)appClient:(ARDAppClient *)client
     didChangeState:(ARDAppClientState)state;
 
 - (void)appClient:(ARDAppClient *)client
     didChangeConnectionState:(RTCIceConnectionState)state;
 
@@ skipping 13 matching lines @@
 
 // Handles connections to the AppRTC server for a given room. Methods on this
 // class should only be called from the main queue.
 @interface ARDAppClient : NSObject
 
 // If |shouldGetStats| is true, stats will be reported in 1s intervals through
 // the delegate.
 @property(nonatomic, assign) BOOL shouldGetStats;
 @property(nonatomic, readonly) ARDAppClientState state;
 @property(nonatomic, weak) id<ARDAppClientDelegate> delegate;
-
 // Convenience constructor since all expected use cases will need a delegate
 // in order to receive remote tracks.
 - (instancetype)initWithDelegate:(id<ARDAppClientDelegate>)delegate;
 
+// Sets camera constraints.
+- (void)setCameraConstraints:(RTCMediaConstraints *)mediaConstraints;
+
 // Establishes a connection with the AppRTC servers for the given room id.
 // If |isLoopback| is true, the call will connect to itself.
 // If |isAudioOnly| is true, video will be disabled for the call.
 // If |shouldMakeAecDump| is true, an aecdump will be created for the call.
 // If |shouldUseLevelControl| is true, the level controller will be used
 // in the call.
 - (void)connectToRoomWithId:(NSString *)roomId
                  isLoopback:(BOOL)isLoopback
                 isAudioOnly:(BOOL)isAudioOnly
           shouldMakeAecDump:(BOOL)shouldMakeAecDump
       shouldUseLevelControl:(BOOL)shouldUseLevelControl;
 
 // Disconnects from the AppRTC servers and any connected clients.
 - (void)disconnect;
 
 @end