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

ios/chrome/browser/payments/payment_items_display_coordinator.mm

 // Copyright 2016 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/payments/payment_items_display_coordinator.h"
 
-#import "base/ios/weak_nsobject.h"
-#include "base/mac/scoped_nsobject.h"
+#include "base/logging.h"
 #include "ios/web/public/payments/payment_request.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface PaymentItemsDisplayCoordinator () {
-  base::WeakNSProtocol<id<PaymentItemsDisplayCoordinatorDelegate>> _delegate;
-  base::scoped_nsobject<PaymentItemsDisplayViewController> _viewController;
+  PaymentItemsDisplayViewController* _viewController;
 }
 
 @end
 
 @implementation PaymentItemsDisplayCoordinator
 
 @synthesize paymentRequest = _paymentRequest;
-
-- (id<PaymentItemsDisplayCoordinatorDelegate>)delegate {
-  return _delegate.get();
-}
-
-- (void)setDelegate:(id<PaymentItemsDisplayCoordinatorDelegate>)delegate {
-  _delegate.reset(delegate);
-}
+@synthesize delegate = _delegate;
 
 - (void)start {
   BOOL payButtonEnabled = _paymentRequest->selected_credit_card() != nil;
-  _viewController.reset([[PaymentItemsDisplayViewController alloc]
+  _viewController = [[PaymentItemsDisplayViewController alloc]
       initWithPaymentRequest:_paymentRequest
-            payButtonEnabled:payButtonEnabled]);
+            payButtonEnabled:payButtonEnabled];
   [_viewController setDelegate:self];
   [_viewController loadModel];
 
   DCHECK([self baseViewController].navigationController);
   [[self baseViewController].navigationController
       pushViewController:_viewController
                 animated:YES];
 }
 
 - (void)stop {
   [[self baseViewController].navigationController
       popViewControllerAnimated:YES];
-  _viewController.reset();
+  _viewController = nil;
 }
 
 #pragma mark - PaymentItemsDisplayViewControllerDelegate
 
 - (void)paymentItemsDisplayViewControllerDidReturn:
     (PaymentItemsDisplayViewController*)controller {
   [_delegate paymentItemsDisplayCoordinatorDidReturn:self];
 }
 
 - (void)paymentItemsDisplayViewControllerDidConfirm:
     (PaymentItemsDisplayViewController*)controller {
   [_delegate paymentItemsDisplayCoordinatorDidConfirm:self];
 }
 
 @end