Make progress notifications an alert.

chrome/browser/notifications/non_persistent_notification_handler.cc

Index: chrome/browser/notifications/non_persistent_notification_handler.cc
diff --git a/chrome/browser/notifications/non_persistent_notification_handler.cc b/chrome/browser/notifications/non_persistent_notification_handler.cc
index e40b79ce2ff3b8c0a604be79cc1ecda96a1f5d79..84ec7804cbf902ee529a7b7d4f11a278c1b58641 100644
--- a/chrome/browser/notifications/non_persistent_notification_handler.cc
+++ b/chrome/browser/notifications/non_persistent_notification_handler.cc
@@ -42,7 +42,6 @@ void NonPersistentNotificationHandler::OpenSettings(Profile* profile) {
 void NonPersistentNotificationHandler::RegisterNotification(
     const std::string& notification_id,
     NotificationDelegate* delegate) {
-  DCHECK_EQ(notifications_.count(notification_id), 0u);
   notifications_[notification_id] =
       scoped_refptr<NotificationDelegate>(delegate);
 }