Download web payment manifests.

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

+// 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.
+
+package org.chromium.chrome.browser.payments;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.content_public.browser.WebContents;
+
+/**
+ * Downloads the payment method manifest based on the payment method name that is a URL with HTTPS
+ * scheme, e.g., https://bobpay.com. The download happens via two consecutive HTTP requests:
+ *
+ * 1) HEAD request for the payment method name. The HTTP response header is parsed for Link header
+ *    that points to the location of the payment method manifest file. Example of a relative
+ *    location:
+ *
+ *        Link: <data/payment-manifest.json>; rel="payment-method-manifest"
+ *
+ *    (This is relative to the payment method URL.) Example of an absolute location:
+ *
+ *        Link: <https://bobpay.com/data/payment-manifest.json>; rel="payment-method-manifest"
+ *
+ *    The absolute location must use HTTPS scheme.
+ *
+ * 2) GET request for the payment method manifest file.
+ */
+@JNINamespace("payments")
+public class PaymentManifestDownloader {
+    /** Interface for the callback to invoke when finished downloading. */
+    public interface ManifestDownloadCallback {
+        /**
+         * Called on successful download of a payment method manifest.
+         *
+         * @param contents The successfully downloaded payment method manifest.
+         */
+        @CalledByNative("ManifestDownloadCallback")
+        void onManifestDownloadSuccess(String contents);
+
+        /** Called on failed download of a payment method manifest. */
+        @CalledByNative("ManifestDownloadCallback")
+        void onManifestDownloadFailure();
+    }
+
+    /**
+     * Downloads the manifest file asynchronously.
+     *
+     * @param webContents The web contents to use as the context for the download. If this goes
+     *                    away, the download is cancelled.
+     * @param methodName  The payment method name that is a URL with HTTPS scheme. Must be a URL and
+     *                    must start with "https://".
+     * @param callback    The callback to invoke when finished downloading.
+     */
+    public static void download(
+            WebContents webContents, String methodName, ManifestDownloadCallback callback) {
+        nativeDownloadPaymentManifest(webContents, methodName, callback);
+    }
+
+    private PaymentManifestDownloader() {}
+
+    private static native void nativeDownloadPaymentManifest(
+            WebContents webContents, String methodName, ManifestDownloadCallback callback);
+}