Provide isAudioEnabled flag to control audio unit.

webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.h

Index: webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.h
diff --git a/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.h b/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.h
index 7dee2d8537bc59552a2a62406443bb3d0b92f209..f3a95548209006d70cdc66da8e623dd793343ae2 100644
--- a/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.h
+++ b/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.h
@@ -10,10 +10,20 @@
 
 #import <UIKit/UIKit.h>
 
+@class ARDVideoCallViewController;
+@protocol ARDVideoCallViewControllerDelegate <NSObject>
+
+- (void)viewControllerDidFinish:(ARDVideoCallViewController *)viewController;
+
+@end
+
 @interface ARDVideoCallViewController : UIViewController
 
+@property(nonatomic, weak) id<ARDVideoCallViewControllerDelegate> delegate;
+
 - (instancetype)initForRoom:(NSString *)room
                  isLoopback:(BOOL)isLoopback
-                isAudioOnly:(BOOL)isAudioOnly;
+                isAudioOnly:(BOOL)isAudioOnly
+                   delegate:(id<ARDVideoCallViewControllerDelegate>)delegate;
 
 @end