Layered component for web payments

components/payments/core/currency_formatter.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 COMPONENTS_PAYMENTS_CURRENCY_FORMATTER_H_
-#define COMPONENTS_PAYMENTS_CURRENCY_FORMATTER_H_
+#ifndef COMPONENTS_PAYMENTS_CORE_CURRENCY_FORMATTER_H_
+#define COMPONENTS_PAYMENTS_CORE_CURRENCY_FORMATTER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
-#include "base/optional.h"
 #include "base/strings/string16.h"
 #include "third_party/icu/source/common/unicode/locid.h"
+#include "third_party/icu/source/common/unicode/unistr.h"
 #include "third_party/icu/source/i18n/unicode/numfmt.h"
 
 namespace payments {
 
 // URI specifying the ISO4217 currency code specification. See for details:
 // https://w3c.github.io/browser-payment-api/#paymentcurrencyamount-dictionary
 extern const char kIso4217CurrencySystem[];
 
 // Currency formatter for amounts, according to a currency code, which typically
 // adheres to [ISO4217] (for example, "USD" for US Dollars).
@@ skipping 11 matching lines @@
   // Formats the |amount| according to the currency code that was set. The
   // result will NOT contain the currency code, nor a subset of it. Rather, the
   // caller of this function should display the currency code separately. The
   // return value may contain non-breaking space and is ready for display. In
   // the case of a failure in initialization of the formatter or during
   // formatter, this method will return |amount|.
   base::string16 Format(const std::string& amount);
 
   // Returns the formatted currency code (<= 6 characters including ellipsis if
   // applicable).
-  std::string formatted_currency_code() { return formatted_currency_code_; }
+  const std::string& formatted_currency_code() const {
+    return formatted_currency_code_;
+  }
 
  private:
   const icu::Locale locale_;
   std::unique_ptr<icu::UnicodeString> currency_code_;
   std::string formatted_currency_code_;
   std::unique_ptr<icu::NumberFormat> icu_formatter_;
 
   DISALLOW_COPY_AND_ASSIGN(CurrencyFormatter);
 };
 
 }  // namespace payments
 
-#endif  // COMPONENTS_PAYMENTS_CURRENCY_FORMATTER_H_
+#endif  // COMPONENTS_PAYMENTS_CORE_CURRENCY_FORMATTER_H_