Wire InstallFinished and add some InstallEvent.waitUntil tests

content/test/data/service_worker/worker_install_fulfilled.js

Index: content/test/data/service_worker/worker_install_fulfilled.js
diff --git a/chrome/test/data/extensions/platform_apps/ephemeral_apps/messaging_receiver/index.js b/content/test/data/service_worker/worker_install_fulfilled.js
similarity index 56%
copy from chrome/test/data/extensions/platform_apps/ephemeral_apps/messaging_receiver/index.js
copy to content/test/data/service_worker/worker_install_fulfilled.js
index dc590d190815d0645476120ece798c9fb5b4db35..74a2cc9ca29a4ebcefd00360f9ba1c255ea81b0d 100644
--- a/chrome/test/data/extensions/platform_apps/ephemeral_apps/messaging_receiver/index.js
+++ b/content/test/data/service_worker/worker_install_fulfilled.js
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-onload = function() {
-  chrome.test.sendMessage('launched');
+this.oninstall = function(event) {
+    event.waitUntil(new Promise(function(r) { setTimeout(r, 5); }));
+    event.waitUntil(1);
 };