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

webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsViewController.h

+/*
+ *  Copyright 2016 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 <UIKit/UIKit.h>
+
+@class ARDMediaConstraintsModel;
+
+NS_ASSUME_NONNULL_BEGIN
+/**
+ * Displays settings options.
+ */
+@interface ARDSettingsViewController : UITableViewController
+
+/**
+ * Creates new instance.
+ *
+ * @param style the table view style that should be used
+ * @param mediaConstraintsModel model class for the media constraints settings.
+ */
+- (instancetype)initWithStyle:(UITableViewStyle)style
+        mediaConstraintsModel:(ARDMediaConstraintsModel *)mediaConstraintsModel;
+
+#pragma mark - Unavailable
+
+- (instancetype)initWithStyle:(UITableViewStyle)style NS_UNAVAILABLE;
+- (instancetype)init NS_UNAVAILABLE;
++ (instancetype) new NS_UNAVAILABLE;
+
+@end
+NS_ASSUME_NONNULL_END