[Payments] Use PaymentInstrument/AutofillPaymentInstrument throughout.

components/payments/core/payment_instrument.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/core/payment_instrument.h"
+
+namespace payments {
+
+PaymentInstrument::PaymentInstrument(const std::string& method_name,
+                                     const base::string16& label,
+                                     const base::string16& sublabel,
+                                     int icon_resource_id)
+    : method_name_(method_name),
+      label_(label),
+      sublabel_(sublabel),
+      icon_resource_id_(icon_resource_id) {}
+
+PaymentInstrument::~PaymentInstrument() {}
+
+}  // namespace payments