PaymentHandler: Implement PaymentRequestEvent constructor.

third_party/WebKit/LayoutTests/http/tests/payments/resources/payment-request-event.js

 importScripts('../../serviceworker/resources/worker-testharness.js');
 
 test(() => {
   assert_true('PaymentRequestEvent' in self);
   assert_inherits(PaymentRequestEvent.prototype, 'waitUntil');
   assert_own_property(PaymentRequestEvent.prototype, 'topLevelOrigin');
   assert_own_property(PaymentRequestEvent.prototype, 'paymentRequestOrigin');
   assert_own_property(PaymentRequestEvent.prototype, 'paymentRequestId');
   assert_own_property(PaymentRequestEvent.prototype, 'methodData');
   assert_own_property(PaymentRequestEvent.prototype, 'total');
   assert_own_property(PaymentRequestEvent.prototype, 'modifiers');
   assert_own_property(PaymentRequestEvent.prototype, 'instrumentKey');
   assert_own_property(PaymentRequestEvent.prototype, 'respondWith');
 });
+
+promise_test(() => {
+  return new Promise(resolve => {
+    var eventWithInit = new PaymentRequestEvent('paymentrequest', {
+      topLevelOrigin: 'https://example.com',
+      paymentRequestOrigin: 'https://example.com',
+      paymentRequestId: 'payment-request-id',
+      methodData: [{
+        supportedMethods: ['basic-card']
+      }],
+      total: {
+        label: 'Total',
+        amount: {
+          currency: 'USD',
+          value: '55.00'
+        }
+      },
+      modifiers: [{
+        supportedMethods: ['basic-card']
+      }],
+      instrumentKey: 'payment-instrument-key'
+    });
+
+    self.addEventListener('paymentrequest', e => {
+      assert_equals(e.topLevelOrigin, 'https://example.com');
+      assert_equals(e.paymentRequestOrigin, 'https://example.com');
+      assert_equals(e.paymentRequestId, 'payment-request-id');
+      assert_equals(e.methodData.length, 1);
+      assert_equals(e.methodData[0].supportedMethods.length, 1);
+      assert_equals(e.methodData[0].supportedMethods[0], 'basic-card');
+      assert_equals(e.total.label, 'Total');
+      assert_equals(e.total.amount.currency, 'USD');
+      assert_equals(e.total.amount.value, '55.00');
+      assert_equals(e.modifiers.length, 1);
+      assert_equals(e.modifiers[0].supportedMethods.length, 1);
+      assert_equals(e.modifiers[0].supportedMethods[0], 'basic-card');
+      assert_equals(e.instrumentKey, 'payment-instrument-key');
+      resolve();
+    });
+
+    self.dispatchEvent(eventWithInit);
+  });
+});