meta: Remave meta_activate_session()

It's not used anywhere, lets drop it.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1689>

src/backends/native/meta-backend-native.c

@@ -580,35 +580,6 @@ meta_activate_vt (int vt, GError **error)
   return meta_launcher_activate_vt (launcher, vt, error);
 }
 
-/**
- * meta_activate_session:
- *
- * Tells mutter to activate the session. When mutter is a
- * display server, this tells logind to switch over to
- * the new session.
- */
-gboolean
-meta_activate_session (void)
-{
-  GError *error = NULL;
-  MetaBackend *backend = meta_get_backend ();
-
-  /* Do nothing. */
-  if (!META_IS_BACKEND_NATIVE (backend))
-    return TRUE;
-
-  MetaBackendNative *native = META_BACKEND_NATIVE (backend);
-
-  if (!meta_launcher_activate_session (native->launcher, &error))
-    {
-      g_warning ("Could not activate session: %s", error->message);
-      g_error_free (error);
-      return FALSE;
-    }
-
-  return TRUE;
-}
-
 void
 meta_backend_native_pause (MetaBackendNative *native)
 {

src/backends/native/meta-launcher.c

@@ -555,17 +555,6 @@ meta_launcher_free (MetaLauncher *self)
   g_slice_free (MetaLauncher, self);
 }
 
-gboolean
-meta_launcher_activate_session (MetaLauncher  *launcher,
-                                GError       **error)
-{
-  if (!login1_session_call_activate_sync (launcher->session_proxy, NULL, error))
-    return FALSE;
-
-  sync_active (launcher);
-  return TRUE;
-}
-
 gboolean
 meta_launcher_activate_vt (MetaLauncher  *launcher,
                            signed char    vt,

src/backends/native/meta-launcher.h

@@ -27,9 +27,6 @@ typedef struct _MetaLauncher MetaLauncher;
 MetaLauncher     *meta_launcher_new                     (GError       **error);
 void              meta_launcher_free                    (MetaLauncher  *self);
 
-gboolean          meta_launcher_activate_session        (MetaLauncher  *self,
-                                                         GError       **error);
-
 gboolean          meta_launcher_activate_vt             (MetaLauncher  *self,
                                                          signed char    vt,
                                                          GError       **error);

src/meta/main.h

@@ -38,9 +38,6 @@ int             meta_run                    (void);
 META_EXPORT
 void            meta_register_with_session  (void);
 
-META_EXPORT
-gboolean        meta_activate_session       (void);  /* Actually defined in meta-backend.c */
-
 META_EXPORT
 gboolean        meta_get_replace_current_wm (void);  /* Actually defined in util.c */