[gimp] app: unref async when removing last callback if idle is pending

[Ell <ell src gnome org>]

commit a779dd38494e89eb91c4dc1fe23fcc5de321137f
Author: Ell <ell_se yahoo com>
Date:   Fri Nov 30 03:09:21 2018 -0500

    app: unref async when removing last callback if idle is pending
    
    In gimp_async_remove_callback(), if removing the last callback
    while the callback idle-source is already pending, cancel the idle
    source and unref the async object (the async is reffed when adding
    the idle source.)

 app/core/gimpasync.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)
---
diff --git a/app/core/gimpasync.c b/app/core/gimpasync.c
index b1f3e932b7..7a57f0f674 100644
--- a/app/core/gimpasync.c
+++ b/app/core/gimpasync.c
@@ -467,7 +467,8 @@ gimp_async_remove_callback (GimpAsync         *async,
                             GimpAsyncCallback  callback,
                             gpointer           data)
 {
-  GList *iter;
+  GList    *iter;
+  gboolean  unref_async = FALSE;
 
   g_return_if_fail (GIMP_IS_ASYNC (async));
   g_return_if_fail (callback != NULL);
@@ -492,7 +493,18 @@ gimp_async_remove_callback (GimpAsync         *async,
       iter = next;
     }
 
+  if (g_queue_is_empty (&async->priv->callbacks) && async->priv->idle_id)
+    {
+      g_source_remove (async->priv->idle_id);
+      async->priv->idle_id = 0;
+
+      unref_async = TRUE;
+    }
+
   g_mutex_unlock (&async->priv->mutex);
+
+  if (unref_async)
+    g_object_unref (async);
 }
 
 /* checks if 'async' is in the "stopped" state.