[Web Payment] Empty cross-platform Android payment app factory.

This patch adds the skeleton code for a payment app factory for Android
payment apps. The new factory is disabled by default, but can be enabled
via chrome://flags/#enable-web-payments-experimental-features drop-down
or --enable-features=CrossPlatformAndroidPaymentAppFactory command line
flag. When enabled, the new factory does not return any payment apps in
this patch.

Bug: 1061503
Change-Id: Iea19c68889be77d5083f86d2b9063db64de38cd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2299855
Commit-Queue: Rouslan Solomakhin <rouslan@chromium.org>
Reviewed-by: Sahel Sharify <sahel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798471}

components/payments/content/BUILD.gn

@@ -8,6 +8,8 @@ static_library("content") {
     "android_app_communication.h",
     "android_payment_app.cc",
     "android_payment_app.h",
+    "android_payment_app_factory.cc",
+    "android_payment_app_factory.h",
     "autofill_payment_app.cc",
     "autofill_payment_app.h",
     "autofill_payment_app_factory.cc",

components/payments/content/android_payment_app_factory.cc

+// Copyright 2020 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/content/android_payment_app_factory.h"
+
+#include <utility>
+
+#include "base/memory/weak_ptr.h"
+#include "base/supports_user_data.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/web_contents.h"
+
+namespace payments {
+namespace {
+
+class AppFinder : public base::SupportsUserData::Data {
+ public:
+  static base::WeakPtr<AppFinder> CreateAndSetOwnedBy(
+      base::SupportsUserData* owner) {
+    DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+    DCHECK(owner);
+    auto owned = std::make_unique<AppFinder>(owner);
+    auto weak_ptr = owned->weak_ptr_factory_.GetWeakPtr();
+    const void* key = owned.get();
+    owner->SetUserData(key, std::move(owned));
+    return weak_ptr;
+  }
+
+  explicit AppFinder(base::SupportsUserData* owner) : owner_(owner) {}
+  ~AppFinder() override = default;
+
+  AppFinder(const AppFinder& other) = delete;
+  AppFinder& operator=(const AppFinder& other) = delete;
+
+  void FindApps(base::WeakPtr<PaymentAppFactory::Delegate> delegate) {
+    DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+    DCHECK_EQ(nullptr, delegate_.get());
+    DCHECK_NE(nullptr, delegate.get());
+
+    delegate_ = delegate;
+
+    OnDoneCreatingPaymentApps();
+  }
+
+ private:
+  void OnDoneCreatingPaymentApps() {
+    if (delegate_)
+      delegate_->OnDoneCreatingPaymentApps();
+
+    owner_->RemoveUserData(this);
+  }
+
+  base::SupportsUserData* owner_;
+  base::WeakPtr<PaymentAppFactory::Delegate> delegate_;
+
+  base::WeakPtrFactory<AppFinder> weak_ptr_factory_{this};
+};
+
+}  // namespace
+
+AndroidPaymentAppFactory::AndroidPaymentAppFactory()
+    : PaymentAppFactory(PaymentApp::Type::NATIVE_MOBILE_APP) {}
+
+AndroidPaymentAppFactory::~AndroidPaymentAppFactory() = default;
+
+void AndroidPaymentAppFactory::Create(base::WeakPtr<Delegate> delegate) {
+  auto app_finder = AppFinder::CreateAndSetOwnedBy(delegate->GetWebContents());
+  app_finder->FindApps(delegate);
+}
+
+}  // namespace payments

components/payments/content/android_payment_app_factory.h

+// Copyright 2020 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_APP_FACTORY_H_
+#define COMPONENTS_PAYMENTS_CONTENT_ANDROID_PAYMENT_APP_FACTORY_H_
+
+#include "components/payments/content/payment_app_factory.h"
+
+namespace payments {
+
+// Retrieves Android payment apps.
+class AndroidPaymentAppFactory : public PaymentAppFactory {
+ public:
+  AndroidPaymentAppFactory();
+  ~AndroidPaymentAppFactory() override;
+
+  AndroidPaymentAppFactory(const AndroidPaymentAppFactory& other) = delete;
+  AndroidPaymentAppFactory& operator=(const AndroidPaymentAppFactory& other) =
+      delete;
+
+  // PaymentAppFactory:
+  void Create(base::WeakPtr<Delegate> delegate) override;
+};
+
+}  // namespace payments
+
+#endif  // COMPONENTS_PAYMENTS_CONTENT_ANDROID_PAYMENT_APP_FACTORY_H_

components/payments/content/payment_app_service.cc

@@ -5,9 +5,12 @@
 #include "components/payments/content/payment_app_service.h"
 
 #include "base/feature_list.h"
+#include "components/payments/content/android_payment_app_factory.h"
 #include "components/payments/content/autofill_payment_app_factory.h"
 #include "components/payments/content/payment_app.h"
 #include "components/payments/content/service_worker_payment_app_factory.h"
+#include "components/payments/core/features.h"
+#include "components/payments/core/payments_experimental_features.h"
 #include "content/public/common/content_features.h"
 
 namespace payments {
@@ -15,8 +18,17 @@ namespace payments {
 PaymentAppService::PaymentAppService() {
   factories_.emplace_back(std::make_unique<AutofillPaymentAppFactory>());
 
-  if (base::FeatureList::IsEnabled(::features::kServiceWorkerPaymentApps))
+  if (base::FeatureList::IsEnabled(::features::kServiceWorkerPaymentApps)) {
     factories_.emplace_back(std::make_unique<ServiceWorkerPaymentAppFactory>());
+  }
+
+  // TODO(https://crbug.com/1022512): Review the feature flag name when
+  // AndroidPaymentAppFactory works on Android OS with generic 3rd party payment
+  // apps. (Currently it works only on Chrome OS with app store billing payment
+  // methods.)
+  if (PaymentsExperimentalFeatures::IsEnabled(features::kAppStoreBilling)) {
+    factories_.emplace_back(std::make_unique<AndroidPaymentAppFactory>());
+  }
 }
 
 PaymentAppService::~PaymentAppService() = default;