[Payments] Implement openWindow for service worker based payment handler

content/test/data/payments/payment_app.js

 // 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.
 
 self.addEventListener('paymentrequest', e => {
   e.waitUntil(clients.matchAll({includeUncontrolled: true}).then(clients => {
     clients.forEach(client => {
       if (client.url.indexOf('payment_app_invocation.html') != -1) {
         client.postMessage(e.topLevelOrigin);
         client.postMessage(e.paymentRequestOrigin);
@@ skipping 26 matching lines @@
         return;
       }
 
       if (e.data.methodName) {
         resolve(e.data);
         return;
       }
     });
 
     // Open a window
-    clients.openWindow('payment_app_window.html')
+    e.openWindow('payment_app_window.html')
       .then(window_client => {
         payment_app_window = window_client;
         maybeSendPaymentRequest();
       })
   }));
 });