renderer-native: Destroy monitor framebuffers when suspending

When suspending (i.e. VT switching away, the GDM gnome-shell instance
gets hidden, or changing user), destroy the onscreen and offscreen
monitor framebuffers. When resuming, the stage views and framebuffers
will be recreated anyway.

https://bugzilla.gnome.org/show_bug.cgi?id=786299

clutter/clutter/clutter-stage-view.c

@@ -267,6 +267,7 @@ clutter_stage_view_set_property (GObject      *object,
       priv->layout = *layout;
       break;
     case PROP_FRAMEBUFFER:
+      g_clear_pointer (&priv->framebuffer, cogl_object_unref);
       priv->framebuffer = g_value_dup_boxed (value);
 #ifndef G_DISABLE_CHECKS
       if (priv->framebuffer)
@@ -284,6 +285,7 @@ clutter_stage_view_set_property (GObject      *object,
 #endif
       break;
     case PROP_OFFSCREEN:
+      g_clear_pointer (&priv->offscreen, cogl_object_unref);
       priv->offscreen = g_value_dup_boxed (value);
       break;
     case PROP_SCALE:
@@ -355,7 +357,7 @@ clutter_stage_view_class_init (ClutterStageViewClass *klass)
                         "Framebuffer used as intermediate buffer",
                         COGL_TYPE_HANDLE,
                         G_PARAM_READWRITE |
-			G_PARAM_CONSTRUCT_ONLY |
+                        G_PARAM_CONSTRUCT |
                         G_PARAM_STATIC_STRINGS);
 
   obj_props[PROP_SCALE] =

src/backends/native/meta-backend-native.c

@@ -668,11 +668,14 @@ meta_backend_native_pause (MetaBackendNative *native)
     meta_backend_get_monitor_manager (backend);
   MetaMonitorManagerKms *monitor_manager_kms =
     META_MONITOR_MANAGER_KMS (monitor_manager);
+  MetaRendererNative *renderer_native =
+    META_RENDERER_NATIVE (meta_backend_get_renderer (backend));
 
   clutter_evdev_release_devices ();
   clutter_egl_freeze_master_clock ();
 
   meta_monitor_manager_kms_pause (monitor_manager_kms);
+  meta_renderer_native_pause (renderer_native);
 }
 
 void meta_backend_native_resume (MetaBackendNative *native)

src/backends/native/meta-renderer-native.c

@@ -1786,6 +1786,24 @@ meta_renderer_native_get_frame_counter (MetaRendererNative *renderer_native)
   return renderer_native->frame_counter;
 }
 
+void
+meta_renderer_native_pause (MetaRendererNative *renderer_native)
+{
+  GList *views;
+  GList *l;
+
+  views = meta_renderer_get_views (META_RENDERER (renderer_native));
+  for (l = views; l; l = l->next)
+    {
+      ClutterStageView *stage_view = l->data;
+
+      g_object_set (G_OBJECT (stage_view),
+                    "framebuffer", NULL,
+                    "offscreen", NULL,
+                    NULL);
+    }
+}
+
 static void
 meta_renderer_native_get_property (GObject    *object,
                                    guint       prop_id,

src/backends/native/meta-renderer-native.h

@@ -71,4 +71,6 @@ void meta_renderer_native_finish_frame (MetaRendererNative *renderer_native);
 
 int64_t meta_renderer_native_get_frame_counter (MetaRendererNative *renderer_native);
 
+void meta_renderer_native_pause (MetaRendererNative *renderer_native);
+
 #endif /* META_RENDERER_NATIVE_H */