[gtk+] application: Protect against double shutdown

[Matthias Clasen <matthiasc src gnome org>]

commit 0049be4e58ef33749d9ddddb58357c5c93125d5d
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jan 15 17:36:13 2016 -0500

    application: Protect against double shutdown
    
    It is not something that can happen normally.
    But if it does, we shouldn't crash.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=760680

 gtk/gtkapplication.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtkapplication.c b/gtk/gtkapplication.c
index b698951..77a4e1c 100644
--- a/gtk/gtkapplication.c
+++ b/gtk/gtkapplication.c
@@ -620,8 +620,7 @@ gtk_application_startup (GApplication *g_application)
 {
   GtkApplication *application = GTK_APPLICATION (g_application);
 
-  G_APPLICATION_CLASS (gtk_application_parent_class)
-    ->startup (g_application);
+  G_APPLICATION_CLASS (gtk_application_parent_class)->startup (g_application);
 
   gtk_action_muxer_insert (application->priv->muxer, "app", G_ACTION_GROUP (application));
 
@@ -638,6 +637,9 @@ gtk_application_shutdown (GApplication *g_application)
 {
   GtkApplication *application = GTK_APPLICATION (g_application);
 
+  if (application->priv->impl == NULL)
+    return;
+
   gtk_application_impl_shutdown (application->priv->impl);
   g_clear_object (&application->priv->impl);
 
@@ -651,8 +653,7 @@ gtk_application_shutdown (GApplication *g_application)
   /* Synchronize the recent manager singleton */
   _gtk_recent_manager_sync ();
 
-  G_APPLICATION_CLASS (gtk_application_parent_class)
-    ->shutdown (g_application);
+  G_APPLICATION_CLASS (gtk_application_parent_class)->shutdown (g_application);
 }
 
 static gboolean