BackgroundSyncManager tracks client registrations

content/test/data/background_sync/background_sync_test_helpers.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.
 
 'use strict';
 
 var resultQueue = new ResultQueue();
 
 // Sends data back to the test. This must be in response to an earlier
 // request, but it's ok to respond asynchronously. The request blocks until
@@ skipping 24 matching lines @@
   navigator.serviceWorker.ready
     .then(function(swRegistration) {
       return swRegistration.sync.register({'tag': tag});
     })
     .then(function(syncRegistration) {
       sendResultToTest('ok - ' + tag + ' registered');
     })
     .catch(sendErrorToTest);
 }
 
+function unregisterOneShot(tag) {
+  navigator.serviceWorker.ready
+    .then(function(swRegistration) {
+      return swRegistration.sync.getRegistration(tag);
+    })
+    .then(function(syncRegistration) {
+      if (!syncRegistration) {
+        sendResultToTest('error - ' + tag + ' not found');
+        return;
+      }
+      return syncRegistration.unregister();
+    })
+    .then(function() {
+      sendResultToTest('ok - ' + tag + ' unregistered');
+    })
+    .catch(sendErrorToTest);
+}
+
+function unregisterOneShotTwice(tag) {
+  navigator.serviceWorker.ready
+    .then(function(swRegistration) {
+      return swRegistration.sync.getRegistration(tag);
+    })
+    .then(function(syncRegistration) {
+      if (!syncRegistration) {
+        sendResultToTest('error - ' + tag + ' not found');
+        return;
+      }
+      return syncRegistration.unregister();
+    })
+    .then(function() {
+      return syncRegistration.unregister();
+    })
+    .then(sendErrorToTest, function() {
+      sendResultToTest('ok - ' + tag + ' failed to unregister twice');
+    })
+    .catch(sendErrorToTest);
+}
+
 function getRegistrationOneShot(tag) {
   navigator.serviceWorker.ready
     .then(function(swRegistration) {
       return swRegistration.sync.getRegistration(tag);
     })
     .then(function(syncRegistration) {
       if (!syncRegistration) {
         sendResultToTest('error - ' + tag + ' not found');
         return;
       }
@@ skipping 67 matching lines @@
 // available, otherwise sends null.
 ResultQueue.prototype.popImmediately = function() {
   sendResultToTest(this.queue.length ? this.queue.pop() : null);
 };
 
 navigator.serviceWorker.addEventListener('message', function(event) {
   var message = event.data;
   if (message.type == 'sync')
     resultQueue.push(message.data);
 }, false);