Add missing header files to GN files

ui/events/ipc/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 
 component("ipc") {
   output_name = "events_ipc"
   sources = [
+    "events_ipc_export.h",
     "latency_info_param_traits.cc",
     "latency_info_param_traits.h",
     "latency_info_param_traits_macros.h",
   ]
 
   defines = [ "EVENTS_IPC_IMPLEMENTATION" ]
 
   deps = [
     "//base",
     "//ipc",
     "//ui/events:events_base",
     "//ui/gfx/ipc/geometry",
   ]
 }