Minimize the delegate dependencies for non persistent notifications.

chrome/browser/notifications/native_notification_delegate.h

+// 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.
+
+#ifndef CHROME_BROWSER_NOTIFICATIONS_NATIVE_NOTIFICATION_DELEGATE_H_
+#define CHROME_BROWSER_NOTIFICATIONS_NATIVE_NOTIFICATION_DELEGATE_H_
+
+#include "chrome/browser/notifications/notification_delegate.h"
+
+// Temporary native notification delegate, it is only used
+// to extract the delegate id.
+// This is an interim state until the work in
+// https://bugs.chromium.org/p/chromium/issues/detail?id=720345
+// is completed. A small delegate shim is needed since the
+// Notification object has a non virtual method (delegate_id) that is
+// used all over the place whose implementation returns delegate->id()
+class NativeNotificationDelegate : public NotificationDelegate {
+ public:
+  explicit NativeNotificationDelegate(const std::string& notification_id)
+      : notification_id_(notification_id) {}
+  std::string id() const override;
+
+ private:
+  ~NativeNotificationDelegate() override = default;
+  const std::string notification_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeNotificationDelegate);
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_NATIVE_NOTIFICATION_DELEGATE_H_