Expose ServiceWorkerRegistration.showNotification() in Service Workers.

LayoutTests/http/tests/notifications/resources/test-helpers.js

 // Supports test-runner control messages being send over |messagePort|, which enable
 // workers to have limited access to TestRunner methods.
 function supportTestRunnerMessagesOnPort(messagePort)
 {
     if (!window.testRunner)
         return;
 
     messagePort.addEventListener('message', function(message) {
         if (message.data.type == 'simulateWebNotificationClick')
             testRunner.simulateWebNotificationClick(message.data.title);
@@ skipping 18 matching lines @@
     supportTestRunnerMessagesOnPort(worker.port);
 
     fetch_tests_from_worker(worker);
 }
 
 // Used by tests to announce that all tests have been registered when they're
 // being ran from a dedicated or shared worker. Not necessary for document tests.
 function isDedicatedOrSharedWorker()
 {
     return false;
-}
+}
+
+// Unregisters, then registers the Service Worker in |script| using |scope|, waits
+// for it to activate and then inserts a message port. Returns a Promise which will
+// be resolved with an object having the worker's registration and port. The
+// Service Worker will be automatically unregistered once the test has completed.
+function getActiveServiceWorkerWithMessagePort(test, script, scope)
+{
+    var registration = null;
+    return service_worker_unregister_and_register(test, script, scope).then(function (swRegistration) {

[Michael van Ouwerkerk, 2015/01/26 16:52:37]

Please don't leave space between 'function' and '(', here or in the rest of the
CL. It's unusual in general, and inconsistent within these files.

[Peter Beverloo, 2015/01/27 11:16:56]

Done.

+        registration = swRegistration;
+        add_completion_callback(function() {
+            registration.unregister();
+        });
+
+        return wait_for_state(test, registration.installing, 'activated');
+    }).then(function () {
+        assert_not_equals(registration.active, null, 'The Service Worker needs to be activated.');
+        return new Promise(function (resolve) {
+            var messageChannel = new MessageChannel();
+            messageChannel.port1.addEventListener('message', function(event) {
+                if (event.data == 'ready')
+                    resolve({ registration: registration, port: messageChannel.port1 });
+            });
+
+            registration.active.postMessage(messageChannel.port2, [messageChannel.port2]);
+            messageChannel.port1.start();
+        });
+    });
+}