Add NotificationOptions.actions so websites can provide buttons (blink)

LayoutTests/http/tests/notifications/serviceworker-notificationclick-event-reflection.html

Index: LayoutTests/http/tests/notifications/serviceworker-notificationclick-event-reflection.html
diff --git a/LayoutTests/http/tests/notifications/serviceworker-notificationclick-event-reflection.html b/LayoutTests/http/tests/notifications/serviceworker-notificationclick-event-reflection.html
index 5bf4edf0021dd04b5f0c9be24ecb87ab4db69e2d..b82628b015db09c9a19aa222093b94e7eadafcfd 100644
--- a/LayoutTests/http/tests/notifications/serviceworker-notificationclick-event-reflection.html
+++ b/LayoutTests/http/tests/notifications/serviceworker-notificationclick-event-reflection.html
@@ -33,7 +33,8 @@
                     string: '\uDFFF\u0000\uDBFF',
                     scalar: true },
                   12.15
-              ]
+              ],
+              actions: [{title: "Action 1"}, {title: "Action 2"}, {title: "Action 3"}]
           };
 
           testRunner.setPermission('notifications', 'granted', location.origin, location.origin);
@@ -66,6 +67,10 @@
                   assert_equals(event.data.command, 'click', 'The notification was expected to be clicked.');
 
                   Object.keys(options).forEach(function(key) {
+                      if (key == 'actions') {
+                          // TODO(johnme): actions are not yet serialized properly.
+                          return;
+                      }
                       assert_object_equals(event.data.notification[key], options[key], 'The ' + key + ' field must be the same.');
                   });