Add PlatformWindow/Event related code for Ozone X11.

ui/platform_window/x11/x11_window.gyp

Index: ui/platform_window/x11/x11_window.gyp
diff --git a/ui/platform_window/x11/x11_window.gyp b/ui/platform_window/x11/x11_window.gyp
index 0dd840a5e2bf89219e58b198985ed6d3e03f03db..dfdfbb0d4973deaf263192164207cbc95044ea64 100644
--- a/ui/platform_window/x11/x11_window.gyp
+++ b/ui/platform_window/x11/x11_window.gyp
@@ -19,6 +19,7 @@
       '../../events/events.gyp:events',
       '../../events/platform/events_platform.gyp:events_platform',
       '../../events/platform/x11/x11_events_platform.gyp:x11_events_platform',
+      '../../events/x/events_x.gyp:events_x',
       '../../gfx/x/gfx_x11.gyp:gfx_x11',
       '../platform_window.gyp:platform_window',
     ],
@@ -26,6 +27,8 @@
     'sources': [
       'x11_window.cc',
       'x11_window.h',
+      'x11_window_base.cc',
+      'x11_window_base.h',
       'x11_window_export.h',
     ],
   }],