wayland-protocols: Add pointer_stylus_exists error to zcr_stylus_v1 interface.

third_party/wayland-protocols/include/protocol/stylus-unstable-v1-client-protocol.h

Index: third_party/wayland-protocols/include/protocol/stylus-unstable-v1-client-protocol.h
diff --git a/third_party/wayland-protocols/include/protocol/stylus-unstable-v1-client-protocol.h b/third_party/wayland-protocols/include/protocol/stylus-unstable-v1-client-protocol.h
index ef933147f1d8dc08c35573be0d16c25eaeeb634c..c5e4f425cb8ba3b492e639ec5bb99d3f23c4104d 100644
--- a/third_party/wayland-protocols/include/protocol/stylus-unstable-v1-client-protocol.h
+++ b/third_party/wayland-protocols/include/protocol/stylus-unstable-v1-client-protocol.h
@@ -106,6 +106,16 @@ extern const struct wl_interface zcr_stylus_v1_interface;
  */
 extern const struct wl_interface zcr_pointer_stylus_v1_interface;
 
+#ifndef ZCR_STYLUS_V1_ERROR_ENUM
+#define ZCR_STYLUS_V1_ERROR_ENUM
+enum zcr_stylus_v1_error {
+	/**
+	 * the pointer already has a pointer_stylus object associated
+	 */
+	ZCR_STYLUS_V1_ERROR_POINTER_STYLUS_EXISTS = 0,
+};
+#endif /* ZCR_STYLUS_V1_ERROR_ENUM */
+
 #define ZCR_STYLUS_V1_GET_POINTER_STYLUS	0
 
 /**
@@ -144,7 +154,8 @@ zcr_stylus_v1_destroy(struct zcr_stylus_v1 *zcr_stylus_v1)
  * @ingroup iface_zcr_stylus_v1
  *
  * Create pointer_stylus object. See zcr_pointer_stylus_v1 interface for
- * details.
+ * details. If the given wl_pointer already has a pointer_stylus object
+ * associated, the pointer_stylus_exists protocol error is raised.
  */
 static inline struct zcr_pointer_stylus_v1 *
 zcr_stylus_v1_get_pointer_stylus(struct zcr_stylus_v1 *zcr_stylus_v1, struct wl_pointer *pointer)