[gtk: 1/2] Add proper annotation for gdk_frame_clock_get_refresh_info

[Christoph Reiter <creiter src gnome org>]

commit fe8225e57389554e122baae807fc68aad99e0f9e
Author: Sander Sweers <infirit gmail com>
Date:   Mon Mar 12 14:29:09 2018 +0100

    Add proper annotation for gdk_frame_clock_get_refresh_info
    
    See https://gitlab.gnome.org/GNOME/gtk/issues/77

 gdk/gdkframeclock.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gdk/gdkframeclock.c b/gdk/gdkframeclock.c
index a1f20c40e9..e848a21d5a 100644
--- a/gdk/gdkframeclock.c
+++ b/gdk/gdkframeclock.c
@@ -537,10 +537,10 @@ _gdk_frame_clock_debug_print_timings (GdkFrameClock   *clock,
  * gdk_frame_clock_get_refresh_info:
  * @frame_clock: a #GdkFrameClock
  * @base_time: base time for determining a presentaton time
- * @refresh_interval_return: a location to store the determined refresh
- *  interval, or %NULL. A default refresh interval of 1/60th of
- *  a second will be stored if no history is present.
- * @presentation_time_return: a location to store the next
+ * @refresh_interval_return: (out) (optional): a location to store the
+ * determined refresh interval, or %NULL. A default refresh interval of
+ * 1/60th of a second will be stored if no history is present.
+ * @presentation_time_return: (out): a location to store the next
  *  candidate presentation time after the given base time.
  *  0 will be will be stored if no history is present.
  *