[ObjC ARC] Converts ios/chrome/browser/ui/side_swipe:side_swipe to ARC.

ios/chrome/browser/ui/side_swipe/side_swipe_util.mm

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/ui/side_swipe/side_swipe_util.h"
 
 #import <UIKit/UIKit.h>
 
 #include "ios/chrome/browser/ui/rtl_geometry.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 BOOL IsSwipingBack(UISwipeGestureRecognizerDirection direction) {
   if (UseRTLLayout())
     return direction == UISwipeGestureRecognizerDirectionLeft;
   else
     return direction == UISwipeGestureRecognizerDirectionRight;
 }
 
 BOOL IsSwipingForward(UISwipeGestureRecognizerDirection direction) {
   if (UseRTLLayout())
     return direction == UISwipeGestureRecognizerDirectionRight;
   else
     return direction == UISwipeGestureRecognizerDirectionLeft;
 }