Add PlatformWindow/Event related code for Ozone X11.

ui/ozone/platform/x11/client_native_pixmap_factory_x11.cc

Index: ui/ozone/platform/x11/client_native_pixmap_factory_x11.cc
diff --git a/ui/ozone/platform/wayland/client_native_pixmap_factory_wayland.cc b/ui/ozone/platform/x11/client_native_pixmap_factory_x11.cc
similarity index 68%
copy from ui/ozone/platform/wayland/client_native_pixmap_factory_wayland.cc
copy to ui/ozone/platform/x11/client_native_pixmap_factory_x11.cc
index eeea61baf57332f76b6caba3bf11790980b3b338..b9083e51d911678aa0acd922aa7dbbc8f6ea2563 100644
--- a/ui/ozone/platform/wayland/client_native_pixmap_factory_wayland.cc
+++ b/ui/ozone/platform/x11/client_native_pixmap_factory_x11.cc
@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ui/ozone/platform/wayland/client_native_pixmap_factory_wayland.h"
+#include "ui/ozone/platform/x11/client_native_pixmap_factory_x11.h"
 
 #include "ui/ozone/common/stub_client_native_pixmap_factory.h"
 
 namespace ui {
 
-ClientNativePixmapFactory* CreateClientNativePixmapFactoryWayland() {
+ClientNativePixmapFactory* CreateClientNativePixmapFactoryX11() {
   return CreateStubClientNativePixmapFactory();
 }