[mutter] monitor-config: Handle invalid previous configurations

[Rui Matos <rtcm src gnome org>]

commit 8587f0e80d7da4e8133466571fe4c884293eb700
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Mar 29 21:56:28 2016 +0200

    monitor-config: Handle invalid previous configurations
    
    The previous configuration might not apply because the number of
    enabled outputs when trying to apply it might have changed. This isn't
    a bug so we shouldn't assert. Instead, we can handle it by falling
    back as we would if we didn't have a previous configuration to start
    with.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=764286

 src/backends/meta-monitor-config.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)
---
diff --git a/src/backends/meta-monitor-config.c b/src/backends/meta-monitor-config.c
index e6e3791..a934613 100644
--- a/src/backends/meta-monitor-config.c
+++ b/src/backends/meta-monitor-config.c
@@ -1554,18 +1554,19 @@ meta_monitor_config_restore_previous (MetaMonitorConfig  *self,
       /* The user chose to restore the previous configuration. In this
        * case, restore the previous configuration. */
       MetaConfiguration *prev_config = config_ref (self->previous);
-      apply_configuration (self, prev_config, manager);
+      gboolean ok = apply_configuration (self, prev_config, manager);
       config_unref (prev_config);
 
       /* After this, self->previous contains the rejected configuration.
        * Since it was rejected, nuke it. */
       g_clear_pointer (&self->previous, (GDestroyNotify) config_unref);
+
+      if (ok)
+        return;
     }
-  else
-    {
-      if (!meta_monitor_config_apply_stored (self, manager))
-        meta_monitor_config_make_default (self, manager);
-    }
+
+  if (!meta_monitor_config_apply_stored (self, manager))
+    meta_monitor_config_make_default (self, manager);
 }
 
 static void
@@ -2029,7 +2030,11 @@ meta_monitor_config_assign_crtcs (MetaConfiguration  *config,
 
   all_outputs = meta_monitor_manager_get_outputs (manager,
                                                   &n_outputs);
-  g_assert (n_outputs == config->n_outputs);
+  if (n_outputs != config->n_outputs)
+    {
+      g_hash_table_destroy (assignment.info);
+      return FALSE;
+    }
 
   for (i = 0; i < n_outputs; i++)
     {