Make payment manifest download/parse cross-platform

components/payments/content/android/payment_manifest_downloader.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_CONTENT_ANDROID_PAYMENT_MANIFEST_DOWNLOADER_H_
-#define COMPONENTS_PAYMENTS_CONTENT_ANDROID_PAYMENT_MANIFEST_DOWNLOADER_H_
-
-#include <memory>
-#include <string>
-
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "net/url_request/url_fetcher.h"
-#include "net/url_request/url_fetcher_delegate.h"
-#include "url/gurl.h"
-
-namespace net {
-class URLRequestContextGetter;
-}
-
-namespace payments {
-
-// Downloader of 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.
-//
-// The downloader does not follow redirects. A download succeeds only if both
-// HTTP response codes are 200.
-class PaymentManifestDownloader : public net::URLFetcherDelegate {
- public:
-  // The interface for receiving the result of downloading a manifest.
-  class Delegate {
-   public:
-    // Called when a manifest has been successfully downloaded.
-    virtual void OnManifestDownloadSuccess(const std::string& content) = 0;
-
-    // Called when failed to download the manifest for any reason:
-    //  - HTTP response code is not 200.
-    //  - HTTP response headers are absent.
-    //  - HTTP response headers does not contain Link headers.
-    //  - Link header does not contain rel="payment-method-manifest".
-    //  - Link header does not contain a valid URL.
-    //  - HTTP GET on the manifest URL returns empty content.
-    virtual void OnManifestDownloadFailure() = 0;
-
-   protected:
-    virtual ~Delegate() {}
-  };
-
-  // |delegate| should not be null and must outlive this object. |method_name|
-  // should be a valid URL that starts with "https://".
-  PaymentManifestDownloader(
-      const scoped_refptr<net::URLRequestContextGetter>& context,
-      const GURL& method_name,
-      Delegate* delegate);
-
-  ~PaymentManifestDownloader() override;
-
-  void Download();
-
- private:
-  void InitiateDownload(const GURL& url,
-                        net::URLFetcher::RequestType request_type);
-
-  // net::URLFetcherDelegate
-  void OnURLFetchComplete(const net::URLFetcher* source) override;
-
-  scoped_refptr<net::URLRequestContextGetter> context_;
-  const GURL method_name_;
-
-  // Non-owned. Never null. Outlives this object.
-  Delegate* delegate_;
-
-  bool is_downloading_http_link_header_;
-  std::unique_ptr<net::URLFetcher> fetcher_;
-
-  DISALLOW_COPY_AND_ASSIGN(PaymentManifestDownloader);
-};
-
-}  // namespace payments
-
-#endif  // COMPONENTS_PAYMENTS_CONTENT_ANDROID_PAYMENT_MANIFEST_DOWNLOADER_H_