Add IPC messages for ARC notification

components/arc/common/arc_host_messages.h

 // Copyright 2015 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.
 
 // Messages sent from the ARC instance to the host.
 // Multiply-included message file, hence no include guard.
 
 #include "ipc/ipc_message_macros.h"
 
+// Using relative paths since this file is shared between chromium and android.
+#include "arc_message_param_traits.h"
+#include "arc_notification_types.h"
+
 #define IPC_MESSAGE_START ArcInstanceHostMsgStart
 
 IPC_MESSAGE_CONTROL0(ArcInstanceHostMsg_InstanceReady)
+
+// Notifies that a notification is posted (created or updated) on the container
+// side with the updated notification data.
+// |notification_data| is the data of notification (id, texts, icon and ...).
+IPC_MESSAGE_CONTROL1(ArcInstanceHostMsg_NotificationPosted,
+                     arc::ArcNotificationData /* notification_data */);
+
+// Notifies that a notification is removed on the container side.
+// |key| is the identifier of notification.
+IPC_MESSAGE_CONTROL1(ArcInstanceHostMsg_NotificationRemoved,
+                     std::string /* key */);