[gimp] app: in bucket-fill tool, fix potential leak when computing line-art

[Ell <ell src gnome org>]

commit 2e45c4c8c889d25f3ce3c441e09e02a0dd2a31d3
Author: Ell <ell_se yahoo com>
Date:   Mon Nov 19 10:54:05 2018 -0500

    app: in bucket-fill tool, fix potential leak when computing line-art
    
    In the line-art async function, pass ownership over the resulting
    buffer to the async object, so that the buffer is properly freed in
    case the async in canceled after line-art computation is complete,
    but before the completion callback is called.
    
    Also, clear the tool's async pointer in the completion callback, to
    avoid leaking the last issued async.

 app/tools/gimpbucketfilltool.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)
---
diff --git a/app/tools/gimpbucketfilltool.c b/app/tools/gimpbucketfilltool.c
index 313f474f22..dc3e18b020 100644
--- a/app/tools/gimpbucketfilltool.c
+++ b/app/tools/gimpbucketfilltool.c
@@ -336,8 +336,6 @@ gimp_bucket_fill_tool_start (GimpBucketFillTool *tool,
       tool->priv->async)
     {
       gimp_waitable_wait (GIMP_WAITABLE (tool->priv->async));
-      g_object_unref (tool->priv->async);
-      tool->priv->async = NULL;
     }
 }
 
@@ -706,13 +704,7 @@ gimp_bucket_fill_compute_line_art_async  (GimpAsync      *async,
                                                                data->fill_transparent,
                                                                data->line_art_threshold);
   precompute_data_free (data);
-  if (gimp_async_is_canceled (async))
-    {
-      g_object_unref (line_art);
-      gimp_async_abort (async);
-      return;
-    }
-  gimp_async_finish (async, line_art);
+  gimp_async_finish_full (async, line_art, g_object_unref);
 }
 
 static void
@@ -723,7 +715,9 @@ gimp_bucket_fill_compute_line_art_cb (GimpAsync          *async,
     return;
 
   if (gimp_async_is_finished (async))
-    tool->priv->line_art = gimp_async_get_result (async);
+    tool->priv->line_art = g_object_ref (gimp_async_get_result (async));
+
+  g_clear_object (&tool->priv->async);
 }
 
 static void