Fix flaky TEST PaymentAppBrowserTest.PaymentAppInvocation.

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.
 
-function sendResultToTest(data) {

[arthursonzogni, 2017/03/30 15:15:50]

I removed this function. I don't think it is called.

-  clients.matchAll({includeUncontrolled: true}).then(clients => {
-    clients.forEach(client => {
-      if (client.url.indexOf('payment_app_invocation.html') != -1) {
-        client.postMessage(data);
-      }
-    });
-  });
-}
-
-function getMessageFromPaymentAppWindow() {
-  return new Promise((resolve, reject) => {
-    var listener = self.addEventListener('message', e => {
-      resolve(e.data);
-      self.removeEventListener(listener);
-    });
-  });
-}
-
 self.addEventListener('paymentrequest', e => {
-  var payment_app_window;
-
   // SW -------------------- openWindow() ------------------> payment_app_window
   // SW <----- postMessage('payment_app_window_ready') ------ payment_app_window
   // SW -------- postMessage('payment_app_request') --------> payment_app_window
   // SW <-- postMessage({methodName: 'test', details: {}}) -- payment_app_window
   e.respondWith(new Promise(resolve => {
+    let payment_app_window = undefined;
+    let window_ready = false;
+
+    let maybeSendPaymentRequest = function() {
+      if (payment_app_window && window_ready)
+        payment_app_window.postMessage('payment_app_request');
+    };
+
+    self.addEventListener('message', e => {
+      if (e.data == "payment_app_window_ready") {
+        window_ready = true;
+        maybeSendPaymentRequest();
+        return;
+      }
+
+      if (e.data.methodName) {
+        resolve(e.data);
+        return;
+      }
+    });
+
+    // Open a window
     clients.openWindow('payment_app_window.html')
-        .then(window_client => {
-          payment_app_window = window_client;
-          return getMessageFromPaymentAppWindow();
-        })
-        .then(message => {
-          payment_app_window.postMessage('payment_app_request');
-          return getMessageFromPaymentAppWindow();
-        })
-        .then(message => {
-          resolve(message);
-        });
+      .then(window_client => {
+        payment_app_window = window_client;
+        maybeSendPaymentRequest();
+      })
   }));
 });