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

ios/chrome/browser/payments/payment_request_unittest.mm

 // 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.
 
 #include "ios/chrome/browser/payments/payment_request.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/core/browser/test_personal_data_manager.h"
 #include "components/payments/currency_formatter.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/web/public/payments/payment_request.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 // Tests that the payments::CurrencyFormatter is constructed with the correct
 // currency code and currency system.
 TEST(PaymentRequestTest, CreatesCurrencyFormatterCorrectly) {
   ASSERT_EQ("en", GetApplicationContext()->GetApplicationLocale());
 
   autofill::TestPersonalDataManager personal_data_manager;
 
   std::unique_ptr<web::PaymentRequest> web_payment_request =
       base::MakeUnique<web::PaymentRequest>();
   web_payment_request->details.total.amount.currency =
@@ skipping 18 matching lines @@
   web_payment_request->details.total.amount.currency_system =
       base::ASCIIToUTF16("NOT_ISO4217");
   web_payment_request->details.total.amount.currency =
       base::ASCIIToUTF16("USD");
   PaymentRequest payment_request3(std::move(web_payment_request),
                                   &personal_data_manager);
   currency_formatter = payment_request3.GetOrCreateCurrencyFormatter();
   ASSERT_EQ(base::UTF8ToUTF16("55.00"), currency_formatter->Format("55.00"));
   ASSERT_EQ("USD", currency_formatter->formatted_currency_code());
 }