Add initial support for native Linux desktop notifications

chrome/browser/notifications/message_center_notification_manager.h

Index: chrome/browser/notifications/message_center_notification_manager.h
diff --git a/chrome/browser/notifications/message_center_notification_manager.h b/chrome/browser/notifications/message_center_notification_manager.h
index 589633e44c7c4911dbd6589a88fc562d7c6a2a32..98fe3676c9c1703c8478ced0f33de7da676e31c0 100644
--- a/chrome/browser/notifications/message_center_notification_manager.h
+++ b/chrome/browser/notifications/message_center_notification_manager.h
@@ -28,6 +28,10 @@ class Notification;
 class Profile;
 class ProfileNotification;
 
+#if defined(USE_GLIB) && defined(USE_GIO)
+class DbusNotificationManager;
+#endif
+
 namespace message_center {
 class NotificationBlocker;
 FORWARD_DECLARE_TEST(WebNotificationTrayTest, ManuallyCloseMessageCenter);
@@ -81,6 +85,9 @@ class MessageCenterNotificationManager
   FRIEND_TEST_ALL_PREFIXES(message_center::WebNotificationTrayTest,
                            ManuallyCloseMessageCenter);
 
+#if defined(USE_GLIB) && defined(USE_GIO)
+  std::unique_ptr<DbusNotificationManager> dbus_notification_manager_;
+#endif
   std::unique_ptr<message_center::MessageCenterTrayDelegate> tray_;
   message_center::MessageCenter* message_center_;  // Weak, global.