Wire InstallFinished and add some InstallEvent.waitUntil tests

content/test/data/service_worker/worker_install_rejected.js

Index: content/test/data/service_worker/worker_install_rejected.js
diff --git a/chrome/test/data/extensions/platform_apps/ephemeral_apps/dispatch_event/index.js b/content/test/data/service_worker/worker_install_rejected.js
similarity index 55%
copy from chrome/test/data/extensions/platform_apps/ephemeral_apps/dispatch_event/index.js
copy to content/test/data/service_worker/worker_install_rejected.js
index dc590d190815d0645476120ece798c9fb5b4db35..c57ab6f542fa3e67484d9535f5fffec968d302ff 100644
--- a/chrome/test/data/extensions/platform_apps/ephemeral_apps/dispatch_event/index.js
+++ b/content/test/data/service_worker/worker_install_rejected.js
@@ -2,6 +2,8 @@
 // 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(resolve, reject) {
+        setTimeout(reject, 5);
+    }));
 };