Implement WebPushProvider.unregister() in Chromium.

chrome/test/data/push_messaging/push_test.js

 // Copyright 2014 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 pushData = new FutureData();
+var pushRegistration = null;
 
 // 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
 // the response is sent.
 function sendResultToTest(result) {
   console.log('sendResultToTest: ' + result);
   if (window.domAutomationController) {
     domAutomationController.send('' + result);
   }
 }
@@ skipping 66 matching lines @@
     element.parentNode.removeChild(element);
     sendResultToTest('manifest removed');
   } else {
     sendResultToTest('unable to find manifest element');
   }
 }
 
 function registerPush() {
   navigator.serviceWorker.ready.then(function(swRegistration) {
     return swRegistration.pushManager.register()
-        .then(function(pushRegistration) {
+        .then(function(registration) {
           // TODO: Cleanup once the final API is exposed.
+          pushRegistration = registration;
           var endpoint = pushRegistration.endpoint ||
                          pushRegistration.pushEndpoint;
           var registrationId = pushRegistration.registrationId ||
                                pushRegistration.pushRegistrationId;
           sendResultToTest(endpoint + ' - ' + registrationId);
         });
   }).catch(sendErrorToTest);
 }
 
 function hasPermission() {
   navigator.serviceWorker.ready.then(function(swRegistration) {
     return swRegistration.pushManager.hasPermission()
         .then(function(permission) {
           sendResultToTest('permission status - ' + permission);
         });
   }).catch(sendErrorToTest);
 }
 
 function isControlled() {
   if (navigator.serviceWorker.controller) {
     sendResultToTest('true - is controlled');
   } else {
     sendResultToTest('false - is not controlled');
   }
 }
 
+function unregister() {
+  if (!pushRegistration) {
+    sendResultToTest('unregister error: no registration');
+    return;
+  }
+
+  pushRegistration.unregister().then(function(result) {
+    sendResultToTest('unregister result: ' + result);
+  }, function(error) {
+    sendResultToTest('unregister error: ' + error.name + ': ' + error.message);
+  });
+}
+
 addEventListener('message', function(event) {
   var message = JSON.parse(event.data);
   if (message.type == 'push') {
     pushData.set(message.data);
   }
 }, false);