Add UINavigationController to AppRTCMobile.

webrtc/examples/objc/AppRTCMobile/ios/ARDMainViewController.m

Index: webrtc/examples/objc/AppRTCMobile/ios/ARDMainViewController.m
diff --git a/webrtc/examples/objc/AppRTCMobile/ios/ARDMainViewController.m b/webrtc/examples/objc/AppRTCMobile/ios/ARDMainViewController.m
index e392168dee61b3e2dee72a224c593cad3fc3862e..f7e03bc72f318e7784ae589ceb791655983cb765 100644
--- a/webrtc/examples/objc/AppRTCMobile/ios/ARDMainViewController.m
+++ b/webrtc/examples/objc/AppRTCMobile/ios/ARDMainViewController.m
@@ -21,6 +21,8 @@
 #import "ARDMainView.h"
 #import "ARDVideoCallViewController.h"
 
+static NSString *barButtonImageString = @"ic_settings_black_24dp.png";
+
 @interface ARDMainViewController () <
     ARDMainViewDelegate,
     ARDVideoCallViewControllerDelegate,
@@ -34,9 +36,11 @@
 }
 
 - (void)loadView {
+  self.title = @"AppRTC Mobile";
   _mainView = [[ARDMainView alloc] initWithFrame:CGRectZero];
   _mainView.delegate = self;
   self.view = _mainView;
+  [self addSettingsBarButton];
 
   RTCAudioSessionConfiguration *webRTCConfig =
       [RTCAudioSessionConfiguration webRTCConfiguration];
@@ -51,6 +55,15 @@
   [self setupAudioPlayer];
 }
 
+- (void)addSettingsBarButton {
+  UIBarButtonItem *settingsButton =
+      [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:barButtonImageString]
+                                       style:UIBarButtonItemStylePlain
+                                      target:self
+                                      action:@selector(showSettings:)];
+  self.navigationItem.rightBarButtonItem = settingsButton;
+}
+
 #pragma mark - ARDMainViewDelegate
 
 - (void)mainView:(ARDMainView *)mainView
@@ -155,6 +168,8 @@
 }
 
 #pragma mark - Private
+- (void)showSettings:(id)sender {
+}
 
 - (void)configureAudioSession {
   RTCAudioSessionConfiguration *configuration =