ServiceWorker: Wait for the completion of async tasks on ExtendableMessageEvent

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/indexeddb-worker.js

-var port;
 self.addEventListener('message', function(e) {
     var message = e.data;
     if ('port' in message)
-      doIndexedDBTest(message.port);
+      e.waitUntil(doIndexedDBTest(message.port));
   });
 
 function doIndexedDBTest(port) {
-  var delete_request = indexedDB.deleteDatabase('db');
-  delete_request.onsuccess = function() {
-    var open_request = indexedDB.open('db');
-    open_request.onupgradeneeded = function() {
-      var db = open_request.result;
-      db.createObjectStore('store');
-    };
-    open_request.onsuccess = function() {
-      var db = open_request.result;
-      var tx = db.transaction('store', 'readwrite');
-      var store = tx.objectStore('store');
-      store.put('value', 'key');
-      tx.oncomplete = function() {
-        port.postMessage('done');
+  return new Promise(function(resolve) {
+    var delete_request = indexedDB.deleteDatabase('db');
+    delete_request.onsuccess = function() {
+      var open_request = indexedDB.open('db');
+      open_request.onupgradeneeded = function() {
+        var db = open_request.result;
+        db.createObjectStore('store');
+      };
+      open_request.onsuccess = function() {
+        var db = open_request.result;
+        var tx = db.transaction('store', 'readwrite');
+        var store = tx.objectStore('store');
+        store.put('value', 'key');
+        tx.oncomplete = function() {
+          port.postMessage('done');
+          resolve();
+        };
       };
     };
-  };
+  });
 }