backends/native: Get rendering and swap timings during scanout

Scanout doesn't go through the usual path of compositing and doing
eglSwapBuffers, therefore it doesn't hit the timestamp query placed in
that path. Instead, get the timings by binding the scanout buffer to an
FBO and doing a timestamp query on the FBO.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1762>

src/backends/native/meta-drm-buffer.c

@@ -185,6 +185,27 @@ meta_drm_buffer_get_format (MetaDrmBuffer *buffer)
   return META_DRM_BUFFER_GET_CLASS (buffer)->get_format (buffer);
 }
 
+gboolean
+meta_drm_buffer_supports_fill_timings (MetaDrmBuffer *buffer)
+{
+  return META_DRM_BUFFER_GET_CLASS (buffer)->fill_timings != NULL;
+}
+
+gboolean
+meta_drm_buffer_fill_timings (MetaDrmBuffer  *buffer,
+                              CoglFrameInfo  *info,
+                              GError        **error)
+{
+  if (!meta_drm_buffer_supports_fill_timings (buffer))
+    {
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                           "Buffer doesn't support filling timing info");
+      return FALSE;
+    }
+
+  return META_DRM_BUFFER_GET_CLASS (buffer)->fill_timings (buffer, info, error);
+}
+
 static void
 meta_drm_buffer_get_property (GObject    *object,
                               guint       prop_id,