Minimize the delegate dependencies for non persistent notifications.

chrome/browser/notifications/native_notification_delegate.cc

Index: chrome/browser/notifications/native_notification_delegate.cc
diff --git a/chrome/browser/notifications/native_notification_delegate.cc b/chrome/browser/notifications/native_notification_delegate.cc
new file mode 100644
index 0000000000000000000000000000000000000000..26c0b6d334f3b8e1b156de3ab66ed6dda82e3754
--- /dev/null
+++ b/chrome/browser/notifications/native_notification_delegate.cc
@@ -0,0 +1,9 @@
+// Copyright 2017 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.
+
+#include "chrome/browser/notifications/native_notification_delegate.h"
+
+std::string NativeNotificationDelegate::id() const {
+  return notification_id_;
+}