exo: Implement minimal support for version 6 of XDG shell.

third_party/wayland-protocols/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 config("xdg_shell_protocol_config") {
   include_dirs = [ "include/protocol" ]
 }
 
 source_set("xdg_shell_protocol") {
   sources = [
     "include/protocol/xdg-shell-unstable-v5-client-protocol.h",
     "include/protocol/xdg-shell-unstable-v5-server-protocol.h",
-    "protocol/xdg-shell-protocol.c",
+    "include/protocol/xdg-shell-unstable-v6-client-protocol.h",
+    "include/protocol/xdg-shell-unstable-v6-server-protocol.h",
+    "protocol/xdg-shell-v5-protocol.c",
+    "protocol/xdg-shell-v6-protocol.c",
   ]
 
   deps = [
     "//third_party/wayland:wayland_util",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
 
   public_configs = [ ":xdg_shell_protocol_config" ]
@@ skipping 159 matching lines @@
 
   deps = [
     "//third_party/wayland:wayland_util",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
 
   public_configs = [ ":stylus_protocol_config" ]
 }