Implement WebPushProvider.unregister() in Chromium.

chrome/test/data/push_messaging/push_test.js

Index: chrome/test/data/push_messaging/push_test.js
diff --git a/chrome/test/data/push_messaging/push_test.js b/chrome/test/data/push_messaging/push_test.js
index 2998b199f4601ff712a093575cb8d444c917d8b0..e4fc1c7bbdb80b350bb208579d12314bb96f0cba 100644
--- a/chrome/test/data/push_messaging/push_test.js
+++ b/chrome/test/data/push_messaging/push_test.js
@@ -5,6 +5,7 @@
 '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
@@ -91,9 +92,10 @@ function registerPush() {
   navigator.serviceWorker.ready.then(function(swRegistration) {
     // TODO(mvanouwerkerk): Cleanup once the final API is exposed.
     var pushManager = swRegistration.pushManager || navigator.push;
-    return pushManager.register().then(function(pushRegistration) {
-      sendResultToTest(pushRegistration.pushEndpoint + ' - ' +
-          pushRegistration.pushRegistrationId);
+    return pushManager.register().then(function(registration) {
+      pushRegistration = registration;
+      sendResultToTest(registration.pushEndpoint + ' - ' +
+          registration.pushRegistrationId);
     });
   }).catch(sendErrorToTest);
 }
@@ -116,6 +118,17 @@ function isControlled() {
   }
 }
 
+function unregister() {
+  if (!pushRegistration) {
+    sendErrorToTest('no registration');
+    return;
+  }
+
+  pushRegistration.unregister().then(function(result) {
+    sendResultToTest('unregister result: ' + result);
+  });
+}
+
 addEventListener('message', function(event) {
   var message = JSON.parse(event.data);
   if (message.type == 'push') {