Fix leak of g_object_get value. This was showing up on the

base/mime_util_linux.cc

Index: base/mime_util_linux.cc
diff --git a/base/mime_util_linux.cc b/base/mime_util_linux.cc
index 12dff7acc8005b0859212f4a088afd49c50f96c8..43e5a2d46e31589f7c8bf49a4f0a9011d78c1a16 100644
--- a/base/mime_util_linux.cc
+++ b/base/mime_util_linux.cc
@@ -510,6 +510,7 @@ void InitDefaultThemes() {
                  &gtk_theme_name, NULL);
     default_themes[1] = IconTheme::LoadTheme(gtk_theme_name);
     default_themes[2] = IconTheme::LoadTheme("gnome");
+    g_free(gtk_theme_name);
   }
   // hicolor needs to be last per icon theme spec.
   default_themes[3] = IconTheme::LoadTheme("hicolor");