[metacity] theme: allow NULL as theme name

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 9a935911569a8a1c6f7c798d96f9697bb70031a9
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Wed Jan 21 00:01:07 2015 +0200

    theme: allow NULL as theme name
    
    Theme name == NULL - use current GTK+ theme.

 src/core/prefs.c |    9 +++++----
 src/ui/theme.c   |    2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/src/core/prefs.c b/src/core/prefs.c
index 5d3d23a..1f2c6a0 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -999,15 +999,16 @@ theme_name_handler (GVariant *value,
   *result = NULL; /* ignored */
   string_value = g_variant_get_string (value, NULL);
 
-  if (!string_value || !*string_value)
-    return FALSE;
-
   if (g_strcmp0 (current_theme, string_value) != 0)
     {
       if (current_theme)
         g_free (current_theme);
 
-      current_theme = g_strdup (string_value);
+      if (!string_value || !*string_value)
+        current_theme = NULL;
+      else
+        current_theme = g_strdup (string_value);
+
       queue_changed (META_PREF_THEME);
     }
 
diff --git a/src/ui/theme.c b/src/ui/theme.c
index 132e70b..e875f0e 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -5361,7 +5361,7 @@ meta_theme_set_current (const char *name,
 
   if (!force_reload &&
       meta_current_theme &&
-      strcmp (name, meta_current_theme->name) == 0)
+      g_strcmp0 (name, meta_current_theme->name) == 0)
     return;
 
   err = NULL;