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

ios/chrome/browser/payments/shipping_option_selection_view_controller.h

 // Copyright 2017 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.
 
 #ifndef IOS_CHROME_BROWSER_PAYMENTS_SHIPPING_OPTION_SELECTION_VIEW_CONTROLLER_H_
 #define IOS_CHROME_BROWSER_PAYMENTS_SHIPPING_OPTION_SELECTION_VIEW_CONTROLLER_H_
 
 #import <UIKit/UIKit.h>
 
 #include "ios/chrome/browser/payments/payment_request.h"
@@ skipping 20 matching lines @@
 
 // View controller responsible for presenting the available shipping options
 // for selection by the user and communicating their choice to the supplied
 // delegate.
 @interface ShippingOptionSelectionViewController : CollectionViewController
 
 // Whether or not the view is in a loading state.
 @property(nonatomic, assign) BOOL isLoading;
 
 // The error message to display, if any.
-@property(nonatomic, assign) NSString* errorMessage;
+@property(nonatomic, copy) NSString* errorMessage;
 
 // The delegate to be notified when the user selects a shipping option or
 // returns without selecting one.
 @property(nonatomic, weak) id<ShippingOptionSelectionViewControllerDelegate>
     delegate;
 
 // Initializes this object with an instance of PaymentRequest which owns an
 // instance of web::PaymentRequest as provided by the page invoking the Payment
 // Request API. This object will not take ownership of |paymentRequest|.
 - (instancetype)initWithPaymentRequest:(PaymentRequest*)paymentRequest
     NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)init NS_UNAVAILABLE;
 
 - (instancetype)initWithStyle:(CollectionViewControllerStyle)style
     NS_UNAVAILABLE;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_PAYMENTS_SHIPPING_OPTION_SELECTION_VIEW_CONTROLLER_H_