[gtk/matthiasc/for-master] Add a doc comment for gdk_surface_request_layout

[Matthias Clasen <matthiasc src gnome org>]

commit 338d3ffa133abc9084de1afbcb17ff270c0a6b9c
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Dec 15 14:14:49 2020 -0500

    Add a doc comment for gdk_surface_request_layout

 gdk/gdksurface.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/gdk/gdksurface.c b/gdk/gdksurface.c
index 393329c10f..35c47a3476 100644
--- a/gdk/gdksurface.c
+++ b/gdk/gdksurface.c
@@ -1356,6 +1356,13 @@ gdk_surface_layout_on_clock (GdkFrameClock *clock,
   g_signal_emit (surface, signals[LAYOUT], 0, surface->width, surface->height);
 }
 
+/**
+ * gdk_surface_request_layout:
+ * @surface: a #GdkSurface
+ *
+ * Request a %GDK_FRAME_CLOCK_PHASE_LAYOUT from the surface's
+ * frame clock. See gdk_frame_clock_request_phase().
+ */
 void
 gdk_surface_request_layout (GdkSurface *surface)
 {