[mutter/gnome-3-28] monitor-manager: Cache the last known value of "lid-is-closed"

[Marco Trevisan <marcotrevi src gnome org>]

commit 24b87b364dc5478600b4f14dbf78db082dd75846
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Apr 16 08:57:02 2018 +0000

    monitor-manager: Cache the last known value of "lid-is-closed"
    
    Restarting UPower will make every property of UpClient emit a "notify"
    signal (as a GDBusProxy would). Avoid mutter reconfiguring the displays
    when upower restarts by caching the last known value of "lid-is-closed"
    and only reconfiguring the displays if it actually changed.
    
    This fixes a black out of the screen when UPower restarts.
    
    
    (cherry picked from commit 49b23c749044a855fb3661a0351521f337946c41)

 src/backends/meta-monitor-manager-private.h | 1 +
 src/backends/meta-monitor-manager.c         | 9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/src/backends/meta-monitor-manager-private.h b/src/backends/meta-monitor-manager-private.h
index a7a0671ae..9a59b99c9 100644
--- a/src/backends/meta-monitor-manager-private.h
+++ b/src/backends/meta-monitor-manager-private.h
@@ -181,6 +181,7 @@ struct _MetaMonitorManager
 
   GnomePnpIds *pnp_ids;
   UpClient *up_client;
+  gboolean lid_is_closed;
 
   gulong experimental_features_changed_handler_id;
 
diff --git a/src/backends/meta-monitor-manager.c b/src/backends/meta-monitor-manager.c
index edfa1f64d..ec186009b 100644
--- a/src/backends/meta-monitor-manager.c
+++ b/src/backends/meta-monitor-manager.c
@@ -351,7 +351,13 @@ lid_is_closed_changed (UpClient   *client,
                        gpointer    user_data)
 {
   MetaMonitorManager *manager = user_data;
+  gboolean lid_is_closed;
 
+  lid_is_closed = up_client_get_lid_is_closed (manager->up_client);
+  if (lid_is_closed == manager->lid_is_closed)
+    return;
+
+  manager->lid_is_closed = lid_is_closed;
   meta_monitor_manager_lid_is_closed_changed (manager);
 }
 
@@ -361,7 +367,7 @@ meta_monitor_manager_real_is_lid_closed (MetaMonitorManager *manager)
   if (!manager->up_client)
     return FALSE;
 
-  return up_client_get_lid_is_closed (manager->up_client);
+  return manager->lid_is_closed;
 }
 
 gboolean
@@ -737,6 +743,7 @@ meta_monitor_manager_constructed (GObject *object)
         {
           g_signal_connect_object (manager->up_client, "notify::lid-is-closed",
                                    G_CALLBACK (lid_is_closed_changed), manager, 0);
+          manager->lid_is_closed = up_client_get_lid_is_closed (manager->up_client);
         }
     }