[mutter/wayland] monitor-config: prevent assert that at least one output is connected

[Jasper St. Pierre <jstpierre src gnome org>]

commit e215f3f5eb379ec95b3bae06c32043d94292a4aa
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Tue Oct 15 20:12:05 2013 +0200

    monitor-config: prevent assert that at least one output is connected
    
    Apparently some connector technologies don't distinguish between
    on and off, and there might be valid use cases for running without
    any connected monitor.
    In that case, just avoid any configuration at all.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=709009

 src/backends/meta-monitor-config.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-monitor-config.c b/src/backends/meta-monitor-config.c
index 8150c09..f7ddce5 100644
--- a/src/backends/meta-monitor-config.c
+++ b/src/backends/meta-monitor-config.c
@@ -840,6 +840,9 @@ meta_monitor_config_get_stored (MetaMonitorConfig *self,
   MetaConfiguration key;
   MetaConfiguration *stored;
 
+  if (n_outputs == 0)
+    return NULL;
+
   make_config_key (&key, outputs, n_outputs, -1);
   stored = g_hash_table_lookup (self->configs, &key);
 
@@ -1247,6 +1250,12 @@ meta_monitor_config_make_default (MetaMonitorConfig  *self,
   outputs = meta_monitor_manager_get_outputs (manager, &n_outputs);
   meta_monitor_manager_get_screen_limits (manager, &max_width, &max_height);
 
+  if (n_outputs == 0)
+    {
+      meta_verbose ("No output connected, not applying configuration\n");
+      return;
+    }
+
   default_config = make_default_config (self, outputs, n_outputs, max_width, max_height);
 
   if (default_config != NULL)