PaymentRequest: The currencySystem should be non-nullable.

components/payments/currency_formatter_unittest.cc

 // 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 "components/payments/currency_formatter.h"
 
 #include "base/optional.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 14 matching lines @@
         expected_amount(expected_amount),
         expected_currency_code(expected_currency_code),
         currency_system(currency_system) {}
   ~TestCase() {}
 
   const char* const amount;
   const char* const currency_code;
   const char* const locale_name;
   const std::string expected_amount;
   const char* const expected_currency_code;
-  const base::Optional<std::string> currency_system;
+  const char* const currency_system;
 };
 
 class PaymentsCurrencyFormatterTest : public testing::TestWithParam<TestCase> {
 };
 
 TEST_P(PaymentsCurrencyFormatterTest, IsValidCurrencyFormat) {
   CurrencyFormatter formatter(GetParam().currency_code,
                               GetParam().currency_system,
                               GetParam().locale_name);
   base::string16 output_amount = formatter.Format(GetParam().amount);
@@ skipping 123 matching lines @@
                  "JPY",
                  "http://currsystem.com"),
         TestCase("0.1234",
                  "USD",
                  "en_US",
                  "0.1234",
                  "USD",
                  "http://currsystem.com")));
 
 }  // namespace payments