[mutter] wayland: Add MetaWaylandSurface::destroy signal

[Carlos Garnacho <carlosg src gnome org>]

commit 1acfcbda6c894e42bc80c149954b365e2c2f463e
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Oct 22 14:07:52 2015 +0200

    wayland: Add MetaWaylandSurface::destroy signal
    
    There's places where it would be convenient to add listeners to this,
    so add the signal. The signal is only emitted once during destruction,
    it is convenient for the places where we want notifications at a time
    the object is still alive, as opposed to weak refs which notify after
    the fact.

 src/wayland/meta-wayland-surface.c |   32 ++++++++++++++++++++++++++++++++
 src/wayland/meta-wayland-surface.h |    1 +
 2 files changed, 33 insertions(+), 0 deletions(-)
---
diff --git a/src/wayland/meta-wayland-surface.c b/src/wayland/meta-wayland-surface.c
index 1c2afd9..2958820 100644
--- a/src/wayland/meta-wayland-surface.c
+++ b/src/wayland/meta-wayland-surface.c
@@ -118,6 +118,13 @@ G_DEFINE_TYPE (MetaWaylandSurfaceRoleDND,
                meta_wayland_surface_role_dnd,
                META_TYPE_WAYLAND_SURFACE_ROLE);
 
+enum {
+  SURFACE_DESTROY,
+  N_SURFACE_SIGNALS
+};
+
+guint surface_signals[N_SURFACE_SIGNALS] = { 0 };
+
 static void
 meta_wayland_surface_role_assigned (MetaWaylandSurfaceRole *surface_role);
 
@@ -1796,6 +1803,20 @@ meta_wayland_surface_get_absolute_coordinates (MetaWaylandSurface *surface,
 }
 
 static void
+meta_wayland_surface_dispose (GObject *object)
+{
+  MetaWaylandSurface *surface = META_WAYLAND_SURFACE (object);
+
+  if (!surface->destroying)
+    {
+      g_signal_emit (object, surface_signals[SURFACE_DESTROY], 0);
+      surface->destroying = TRUE;
+    }
+
+  G_OBJECT_CLASS (meta_wayland_surface_parent_class)->dispose (object);
+}
+
+static void
 meta_wayland_surface_init (MetaWaylandSurface *surface)
 {
   surface->pending = g_object_new (META_TYPE_WAYLAND_PENDING_STATE, NULL);
@@ -1804,6 +1825,17 @@ meta_wayland_surface_init (MetaWaylandSurface *surface)
 static void
 meta_wayland_surface_class_init (MetaWaylandSurfaceClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = meta_wayland_surface_dispose;
+
+  surface_signals[SURFACE_DESTROY] =
+    g_signal_new ("destroy",
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  0, NULL, NULL,
+                  g_cclosure_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
 }
 
 static void
diff --git a/src/wayland/meta-wayland-surface.h b/src/wayland/meta-wayland-surface.h
index 9322719..fd1ef41 100644
--- a/src/wayland/meta-wayland-surface.h
+++ b/src/wayland/meta-wayland-surface.h
@@ -207,6 +207,7 @@ struct _MetaWaylandSurface
 
   /* gtk_surface stuff */
   gboolean is_modal;
+  gboolean destroying;
 
   /* wl_subsurface stuff. */
   struct {