[mutter] compositor: Remove 'pre-paint' signal

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit ae7cc0417f845e49a6130631a9d573dc97442e3b
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri May 29 19:26:54 2020 +0200

    compositor: Remove 'pre-paint' signal
    
    It's not used; just use the vfunc directly.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1285

 src/compositor/compositor.c | 20 +-------------------
 1 file changed, 1 insertion(+), 19 deletions(-)
---
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index ff6a6aa73e..a72ecee1cf 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -98,15 +98,6 @@ enum
 
 static GParamSpec *obj_props[N_PROPS] = { NULL, };
 
-enum
-{
-  PRE_PAINT,
-
-  N_SIGNALS
-};
-
-static guint signals[N_SIGNALS];
-
 typedef struct _MetaCompositorPrivate
 {
   GObject parent;
@@ -1129,8 +1120,7 @@ meta_compositor_pre_paint (MetaCompositor *compositor)
 {
   COGL_TRACE_BEGIN_SCOPED (MetaCompositorPrePaint,
                            "Compositor (pre-paint)");
-
-  g_signal_emit (compositor, signals[PRE_PAINT], 0);
+  META_COMPOSITOR_GET_CLASS (compositor)->pre_paint (compositor);
 }
 
 static gboolean
@@ -1335,14 +1325,6 @@ meta_compositor_class_init (MetaCompositorClass *klass)
                          G_PARAM_CONSTRUCT_ONLY |
                          G_PARAM_STATIC_STRINGS);
   g_object_class_install_properties (object_class, N_PROPS, obj_props);
-
-  signals[PRE_PAINT] =
-    g_signal_new ("pre-paint",
-                  G_TYPE_FROM_CLASS (klass),
-                  G_SIGNAL_RUN_LAST,
-                  G_STRUCT_OFFSET (MetaCompositorClass, pre_paint),
-                  NULL, NULL, NULL,
-                  G_TYPE_NONE, 0);
 }
 
 /**