[BackgroundSync] Add browser side support for SyncRegistration.done

content/test/data/background_sync/service_worker.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The "onsync" event currently understands commands (passed as
 // registration tags) coming from the test. Any other tag is
 // passed through to the document unchanged.
 //
 // "delay" - Delays finishing the sync event with event.waitUntil.
 //           Send a postMessage of "completeDelayedOneShot" to finish the
 //           event.
 // "unregister" - Unregisters the sync registration from within the sync event.
 
 'use strict';
 
 var resolveCallback = null;
 var rejectCallback = null;
 
 this.onmessage = function(event) {
-  if (event.data === 'completeDelayedOneShot') {
+  if (event.data['action'] === 'completeDelayedOneShot') {
     if (resolveCallback === null) {
       sendMessageToClients('sync', 'error - resolveCallback is null');
       return;
     }
 
     resolveCallback();
     sendMessageToClients('sync', 'ok - delay completed');
     return;
   }
 
-  if (event.data === 'rejectDelayedOneShot') {
+  if (event.data['action'] === 'rejectDelayedOneShot') {
     if (rejectCallback === null) {
       sendMessageToClients('sync', 'error - rejectCallback is null');
       return;
     }
 
     rejectCallback();
     sendMessageToClients('sync', 'ok - delay rejected');
   }
+
+  if (event.data['action'] === 'notifyWhenDone') {
+    var tag = event.data['tag'];
+    registration.sync.getRegistration(tag)
+      .then(function (syncRegistration) {
+        sendMessageToClients('sync', 'ok - ' + tag + ' done');
+        return syncRegistration.done;
+      })
+      .then(function(success) {
+        sendMessageToClients('sync', tag + " done result: " + success);
+      }, function(error) {
+        sendMessageToClients('sync', tag + " done result: error");
+      })
+      .catch(sendSyncErrorToClients);
+  }
 }
 
 this.onsync = function(event) {
   var eventProperties = [
     // Extract name from toString result: "[object <Class>]"
     Object.prototype.toString.call(event).match(/\s([a-zA-Z]+)/)[1],
     (typeof event.waitUntil)
   ];
 
   if (eventProperties[0] != 'SyncEvent') {
@@ skipping 39 matching lines @@
 
 function sendMessageToClients(type, data) {
   clients.matchAll().then(function(clients) {
     clients.forEach(function(client) {
       client.postMessage({type, data});
     });
   }, function(error) {
     console.log(error);
   });
 }
+
+function sendSyncErrorToClients(error) {
+  sendMessageToClients('sync', error.name + ' - ' + error.message);
+}