Java implementation of PaymentRequest mojo service

chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentApp.java

+// Copyright 2016 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.
+
+package org.chromium.chrome.browser.payments;
+
+import org.chromium.mojom.payments.PaymentItem;
+
+import java.util.List;
+import java.util.Set;
+
+/**
+ * The interface that a payment app implements. A payment app can get its data from Chrome autofill,
+ * Android Pay, or third party apps.
+ */
+public interface PaymentApp {
+    /**
+     * The interface for the requester of instruments.
+     */
+    public interface InstrumentsCallback {
+        /**
+         * Called by this app to provide a list of instruments asynchronously.
+         *
+         * @param app The calling app.
+         * @param instruments The instruments from this app.
+         */
+        void onInstrumentsReady(PaymentApp app, List<PaymentInstrument> instruments);
+    }
+
+    /**
+     * Provides a list of all payment instruments in this app. For example, this can be all credit
+     * cards for the current profile. Can return null or empty list, e.g., if user has no locally
+     * stored credit cards.
+     *
+     * @param items The line items in the payment request. Can be used to filter out instruments
+     *              that, for example, do not have enough funds.
+     * @param callback The object that will receive the list of instruments.
+     */
+    void getInstruments(List<PaymentItem> items, InstrumentsCallback callback);
+
+    /**
+     * Returns a list of all payment method names that this app supports. For example, ["visa",
+     * "mastercard"] in basic card payments. Should return a list of at least one method name.
+     * https://w3c.github.io/browser-payment-api/specs/basic-card-payment.html#method-id
+     *
+     * @return The list of all payment method names that this app supports.
+     */
+    Set<String> getSupportedMethodNames();
+
+    /**
+     * Returns the identifier for this payment app to be saved in user preferences. For example,
+     * this can be "autofill", "https://android.com/pay", or "com.example.app.ExamplePaymentApp".
+     *
+     * @return The identifier for this payment app.
+     */
+    String getIdentifier();
+}