Add tests for the Display operation of the mac notification bridge.

chrome/browser/notifications/notification_test_util.h

Index: chrome/browser/notifications/notification_test_util.h
diff --git a/chrome/browser/notifications/notification_test_util.h b/chrome/browser/notifications/notification_test_util.h
index 66b01e641b5e69d91edbcdaa9c9dfa785b066c9f..5f8ce4b257080734f48c4793c2aefd059da388cd 100644
--- a/chrome/browser/notifications/notification_test_util.h
+++ b/chrome/browser/notifications/notification_test_util.h
@@ -73,4 +73,25 @@ class StubNotificationUIManager : public NotificationUIManager {
   DISALLOW_COPY_AND_ASSIGN(StubNotificationUIManager);
 };
 
+// Generates notification objects with configurable set of parameters.
+class NotificationGenerator {
+ public:
+  // Creates a custom notification.
+  static std::unique_ptr<Notification> CreateNotification(
+      const std::string& title,
+      const std::string& subtitle,
+      const std::string& context,
+      const std::string& button1,
+      const std::string& button2,
+      message_center::NotificationType type);
+
+  // Creates a completly predefined notification for |type|.
+  static std::unique_ptr<Notification> CreateNotification(
+      message_center::NotificationType type);
+
+ private:
+  // only static methods allowed.
+  DISALLOW_IMPLICIT_CONSTRUCTORS(NotificationGenerator);
+};
+
 #endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_TEST_UTIL_H_