Remove non-ARC code from the codebase.

webrtc/examples/objc/AppRTCMobile/mac/APPRTCAppDelegate.m

 /*
  *  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.
  */
 
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
 #import "APPRTCAppDelegate.h"
 #import "APPRTCViewController.h"
 #import "WebRTC/RTCSSLAdapter.h"
 
 @interface APPRTCAppDelegate () <NSWindowDelegate>
 @end
 
 @implementation APPRTCAppDelegate {
   APPRTCViewController* _viewController;
   NSWindow* _window;
@@ skipping 25 matching lines @@
 #pragma mark - NSWindow
 
 - (void)windowWillClose:(NSNotification*)notification {
   [_viewController windowWillClose:notification];
   RTCCleanupSSL();
   [NSApp terminate:self];
 }
 
 @end