[gnome-software] trivial: Fix a small memory leak when setting custom CSS

[Richard Hughes <rhughes src gnome org>]

commit 3583380aeb9c7ae3b3276668b5f89ebf579c8b0b
Author: Richard Hughes <richard hughsie com>
Date:   Wed May 18 21:00:16 2016 +0100

    trivial: Fix a small memory leak when setting custom CSS

 src/gs-common.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/gs-common.c b/src/gs-common.c
index f3281bf..8ea7866 100644
--- a/src/gs-common.c
+++ b/src/gs-common.c
@@ -680,11 +680,11 @@ gs_utils_widget_set_custom_css (GsApp *app, GtkWidget *widget, const gchar *meta
 {
        GPtrArray *key_colors;
        GString *str = g_string_sized_new (1024);
-       GString *css_str = g_string_new ("");
        GtkStyleContext *context;
        const gchar *css;
        guint i;
        g_autofree gchar *class_name = NULL;
+       g_autoptr(GString) css_str = NULL;
        g_autoptr(GtkCssProvider) provider = NULL;
 
        g_return_if_fail (GS_IS_APP (app));