[glib/application-replace] Add a GApplication::name-lost signal

[Matthias Clasen <matthiasc src gnome org>]

commit d5525e18b9fe1eb88cab907a9126aab086d96093
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Aug 18 19:42:21 2018 -0400

    Add a GApplication::name-lost signal
    
    The default handler for this just calls g_application_quit(),
    but applications may want to connect and do cleanup or
    state-saving here.

 gio/gapplication.c          | 26 ++++++++++++++++++++++++++
 gio/gapplication.h          |  3 ++-
 gio/gapplicationimpl-dbus.c |  2 +-
 3 files changed, 29 insertions(+), 2 deletions(-)
---
diff --git a/gio/gapplication.c b/gio/gapplication.c
index a3929a15b..6543ee354 100644
--- a/gio/gapplication.c
+++ b/gio/gapplication.c
@@ -212,6 +212,7 @@
  *     @dbus_register vfunc. Since: 2.34
  * @handle_local_options: invoked locally after the parsing of the commandline
  *  options has occurred. Since: 2.40
+ * @name_lost: invoked when another instance is taking over name. Since: 2.58
  *
  * Virtual function table for #GApplication.
  *
@@ -277,6 +278,7 @@ enum
   SIGNAL_ACTION,
   SIGNAL_COMMAND_LINE,
   SIGNAL_HANDLE_LOCAL_OPTIONS,
+  SIGNAL_NAME_LOST,
   NR_SIGNALS
 };
 
@@ -1194,6 +1196,12 @@ g_application_real_dbus_unregister (GApplication    *application,
 {
 }
 
+static void
+g_application_real_name_lost (GApplication *application)
+{
+  g_application_quit (application);
+}
+
 /* GObject implementation stuff {{{1 */
 static void
 g_application_set_property (GObject      *object,
@@ -1451,6 +1459,7 @@ g_application_class_init (GApplicationClass *class)
   class->add_platform_data = g_application_real_add_platform_data;
   class->dbus_register = g_application_real_dbus_register;
   class->dbus_unregister = g_application_real_dbus_unregister;
+  class->name_lost = g_application_real_name_lost;
 
   g_object_class_install_property (object_class, PROP_APPLICATION_ID,
     g_param_spec_string ("application-id",
@@ -1645,6 +1654,23 @@ g_application_class_init (GApplicationClass *class)
                   g_application_handle_local_options_accumulator, NULL, NULL,
                   G_TYPE_INT, 1, G_TYPE_VARIANT_DICT);
 
+  /**
+   * GApplication::name-lost:
+   * @application: the application
+   *
+   * The ::name-lost signal is emitted only on the registered primary instance
+   * when a new instance has taken over. This can only happen if the application
+   * is using the %G_APPLICATION_ALLOW_REPLACEMENT flag.
+   *
+   * The default handler for this signal calls g_application_quit().
+   *
+   * Since: 2.58
+   */
+  g_application_signals[SIGNAL_NAME_LOST] =
+    g_signal_new (I_("name-lost"), G_TYPE_APPLICATION, G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GApplicationClass, name_lost),
+                  NULL, NULL, g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0);
+
 }
 
 /* Application ID validity {{{1 */
diff --git a/gio/gapplication.h b/gio/gapplication.h
index cdb93655a..553df0d19 100644
--- a/gio/gapplication.h
+++ b/gio/gapplication.h
@@ -112,9 +112,10 @@ struct _GApplicationClass
                                                      const gchar               *object_path);
   gint                      (* handle_local_options)(GApplication              *application,
                                                      GVariantDict              *options);
+  void                      (* name_lost)           (GApplication              *application);
 
   /*< private >*/
-  gpointer padding[8];
+  gpointer padding[7];
 };
 
 GLIB_AVAILABLE_IN_ALL
diff --git a/gio/gapplicationimpl-dbus.c b/gio/gapplicationimpl-dbus.c
index fc569429b..ea3307073 100644
--- a/gio/gapplicationimpl-dbus.c
+++ b/gio/gapplicationimpl-dbus.c
@@ -343,7 +343,7 @@ name_lost (GDBusConnection *bus,
 
   impl->primary = FALSE;
   g_application_impl_stop_primary (impl);
-  g_application_quit (impl->app);
+  g_signal_emit_by_name (impl->app, "name-lost");
 }
 
 /* Attempt to become the primary instance.