Add a portal backend for GNotification

This talks to the org.freedesktop.portal.Notification portal
instead of directly to gnome-shell.

https://bugzilla.gnome.org/show_bug.cgi?id=768498

gio/Makefile.am

@@ -263,6 +263,7 @@ unix_sources = \
 	gcontenttypeprivate.h 	\
 	gfdonotificationbackend.c \
 	ggtknotificationbackend.c \
+	gportalnotificationbackend.c \
 	$(NULL)
 
 if OS_COCOA

gio/giomodule.c

@@ -915,6 +915,7 @@ extern GType _g_network_monitor_nm_get_type (void);
 #ifdef G_OS_UNIX
 extern GType g_fdo_notification_backend_get_type (void);
 extern GType g_gtk_notification_backend_get_type (void);
+extern GType g_portal_notification_backend_get_type (void);
 #endif
 
 #ifdef HAVE_COCOA
@@ -1116,6 +1117,7 @@ _g_io_modules_ensure_loaded (void)
       g_type_ensure (_g_unix_volume_monitor_get_type ());
       g_type_ensure (g_fdo_notification_backend_get_type ());
       g_type_ensure (g_gtk_notification_backend_get_type ());
+      g_type_ensure (g_portal_notification_backend_get_type ());
 #endif
 #ifdef HAVE_COCOA
       g_type_ensure (g_cocoa_notification_backend_get_type ());

gio/gportalnotificationbackend.c

@@ -0,0 +1,97 @@
+/*
+* Copyright © 2016 Red Hat, Inc.
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation; either
+* version 2 of the License, or (at your option) any later version.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General
+* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+*
+* Author: Matthias Clasen
+*/
+
+#include "config.h"
+#include "gnotificationbackend.h"
+
+#include "giomodule-priv.h"
+#include "gdbusconnection.h"
+#include "gapplication.h"
+#include "gnotification-private.h"
+#include "gportalsupport.h"
+
+#define G_TYPE_PORTAL_NOTIFICATION_BACKEND  (g_portal_notification_backend_get_type ())
+#define G_PORTAL_NOTIFICATION_BACKEND(o)    (G_TYPE_CHECK_INSTANCE_CAST ((o), G_TYPE_PORTAL_NOTIFICATION_BACKEND, GPortalNotificationBackend))
+
+typedef struct _GPortalNotificationBackend GPortalNotificationBackend;
+typedef GNotificationBackendClass       GPortalNotificationBackendClass;
+
+struct _GPortalNotificationBackend
+{
+  GNotificationBackend parent;
+};
+
+GType g_portal_notification_backend_get_type (void);
+
+G_DEFINE_TYPE_WITH_CODE (GPortalNotificationBackend, g_portal_notification_backend, G_TYPE_NOTIFICATION_BACKEND,
+  _g_io_modules_ensure_extension_points_registered ();
+  g_io_extension_point_implement (G_NOTIFICATION_BACKEND_EXTENSION_POINT_NAME,
+                                 g_define_type_id, "portal", 110))
+
+static gboolean
+g_portal_notification_backend_is_supported (void)
+{
+  return glib_should_use_portal ();
+}
+
+static void
+g_portal_notification_backend_send_notification (GNotificationBackend *backend,
+                                                 const gchar          *id,
+                                                 GNotification        *notification)
+{
+  g_dbus_connection_call (backend->dbus_connection,
+                          "org.freedesktop.portal.Desktop",
+                          "/org/freedesktop/portal/desktop",
+                          "org.freedesktop.portal.Notification",
+                          "AddNotification",
+                          g_variant_new ("(s@a{sv})",
+                                         id,
+                                         g_notification_serialize (notification)),
+                          G_VARIANT_TYPE_UNIT,
+                          G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+}
+
+static void
+g_portal_notification_backend_withdraw_notification (GNotificationBackend *backend,
+                                                     const gchar          *id)
+{
+  g_dbus_connection_call (backend->dbus_connection,
+                          "org.freedesktop.portal.Desktop",
+                          "/org/freedesktop/portal/desktop",
+                          "org.freedesktop.portal.Notification",
+                          "RemoveNotification",
+                          g_variant_new ("(s)", id),
+                          G_VARIANT_TYPE_UNIT,
+                          G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+}
+
+static void
+g_portal_notification_backend_init (GPortalNotificationBackend *backend)
+{
+}
+
+static void
+g_portal_notification_backend_class_init (GPortalNotificationBackendClass *class)
+{
+  GNotificationBackendClass *backend_class = G_NOTIFICATION_BACKEND_CLASS (class);
+
+  backend_class->is_supported = g_portal_notification_backend_is_supported;
+  backend_class->send_notification = g_portal_notification_backend_send_notification;
+  backend_class->withdraw_notification = g_portal_notification_backend_withdraw_notification;
+}