backends/native: Remove unused meta_gpu_kms_wait_for_flip and more

Remove unused function `meta_gpu_kms_wait_for_flip` and other code which
only existed to support `meta_gpu_kms_wait_for_flip`.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1388

src/backends/native/meta-gpu-kms.c

@@ -183,16 +183,6 @@ timespec_to_nanoseconds (const struct timespec *ts)
   return ((int64_t) ts->tv_sec) * one_billion + ts->tv_nsec;
 }
 
-gboolean
-meta_gpu_kms_wait_for_flip (MetaGpuKms *gpu_kms,
-                            GError    **error)
-{
-  if (meta_kms_device_dispatch_sync (gpu_kms->kms_device, error) < 0)
-    return FALSE;
-
-  return TRUE;
-}
-
 MetaKmsDevice *
 meta_gpu_kms_get_kms_device (MetaGpuKms *gpu_kms)
 {

src/backends/native/meta-gpu-kms.h

@@ -48,9 +48,6 @@ gboolean meta_gpu_kms_is_crtc_active (MetaGpuKms *gpu_kms,
 gboolean meta_gpu_kms_is_boot_vga (MetaGpuKms *gpu_kms);
 gboolean meta_gpu_kms_is_platform_device (MetaGpuKms *gpu_kms);
 
-gboolean meta_gpu_kms_wait_for_flip (MetaGpuKms *gpu_kms,
-                                     GError    **error);
-
 MetaKmsDevice * meta_gpu_kms_get_kms_device (MetaGpuKms *gpu_kms);
 
 int meta_gpu_kms_get_fd (MetaGpuKms *gpu_kms);

src/backends/native/meta-kms-device.c

@@ -174,53 +174,6 @@ meta_kms_device_predict_states_in_impl (MetaKmsDevice *device,
   meta_kms_impl_device_predict_states (impl_device, update);
 }
 
-static gpointer
-dispatch_in_impl (MetaKmsImpl  *impl,
-                  gpointer      user_data,
-                  GError      **error)
-{
-  MetaKmsImplDevice *impl_device = META_KMS_IMPL_DEVICE (user_data);
-  gboolean ret;
-
-  ret = meta_kms_impl_device_dispatch (impl_device, error);
-  return GINT_TO_POINTER (ret);
-}
-
-static gpointer
-dispatch_idle_in_impl (MetaKmsImpl  *impl,
-                       gpointer      user_data,
-                       GError      **error)
-{
-  meta_kms_impl_dispatch_idle (impl);
-
-  return GINT_TO_POINTER (TRUE);
-}
-
-int
-meta_kms_device_dispatch_sync (MetaKmsDevice  *device,
-                               GError        **error)
-{
-  int callback_count;
-
-  if (!meta_kms_run_impl_task_sync (device->kms,
-                                    dispatch_idle_in_impl,
-                                    device->impl_device,
-                                    error))
-    return -1;
-
-  callback_count = meta_kms_flush_callbacks (device->kms);
-  if (callback_count > 0)
-    return TRUE;
-
-  if (!meta_kms_run_impl_task_sync (device->kms,
-                                    dispatch_in_impl,
-                                    device->impl_device,
-                                    error))
-    return -1;
-
-  return meta_kms_flush_callbacks (device->kms);
-}
-
 void
 meta_kms_device_add_fake_plane_in_impl (MetaKmsDevice    *device,
                                         MetaKmsPlaneType  plane_type,

src/backends/native/meta-kms-device.h

@@ -49,9 +49,6 @@ MetaKmsPlane * meta_kms_device_get_primary_plane_for (MetaKmsDevice *device,
 MetaKmsPlane * meta_kms_device_get_cursor_plane_for (MetaKmsDevice *device,
                                                      MetaKmsCrtc   *crtc);
 
-int meta_kms_device_dispatch_sync (MetaKmsDevice  *device,
-                                   GError        **error);
-
 MetaKmsDevice * meta_kms_device_new (MetaKms            *kms,
                                      const char         *path,
                                      MetaKmsDeviceFlag   flags,

src/backends/native/meta-kms-private.h

@@ -36,8 +36,6 @@ void meta_kms_queue_callback (MetaKms         *kms,
                               gpointer         user_data,
                               GDestroyNotify   user_data_destroy);
 
-int meta_kms_flush_callbacks (MetaKms *kms);
-
 gpointer meta_kms_run_impl_task_sync (MetaKms              *kms,
                                       MetaKmsImplTaskFunc   func,
                                       gpointer              user_data,

src/backends/native/meta-kms.c

@@ -318,17 +318,6 @@ meta_kms_queue_callback (MetaKms         *kms,
     kms->callback_source_id = g_idle_add (callback_idle, kms);
 }
 
-int
-meta_kms_flush_callbacks (MetaKms *kms)
-{
-  int callback_count;
-
-  callback_count = flush_callbacks (kms);
-  g_clear_handle_id (&kms->callback_source_id, g_source_remove);
-
-  return callback_count;
-}
-
 gpointer
 meta_kms_run_impl_task_sync (MetaKms              *kms,
                              MetaKmsImplTaskFunc   func,