[PATCH] 'ui::OzonePlatform::Initialize' called multiple times simultanio...

...usly

With option --single-process this function is called two times simultaniously from different threads.

Observed error is
  '[0806/070136:FATAL:ozone_display.cc(26)] Check failed: Replacing set OzoneDisplay implementation.'

Stack trace of one call is
(gdb) bt
   from /usr/lib/xwalk/libwayland.so
    at ../../ozone/platform/ozone_platform_wayland.cc:26
    at ../../ozone/platform/ozone_platform_wayland.cc:58
   from /usr/lib/xwalk/libozone.so
   from /usr/lib/xwalk/libgl_wrapper.so
   from /usr/lib/xwalk/libgl_wrapper.so
    () from /usr/lib/xwalk/libcontent.so
    at ../../content/gpu/in_process_gpu_thread.cc:26

and another
(gdb) bt
   from /usr/lib/xwalk/libwayland.so
    at ../../ozone/platform/ozone_platform_wayland.cc:26
    at ../../ozone/platform/ozone_platform_wayland.cc:58
   from /usr/lib/xwalk/libozone.so
   from /usr/lib/xwalk/libcontent.so
    at ../../content/browser/startup_task_runner.cc:45
   from /usr/lib/xwalk/libcontent.so
    parameters=...) at ../../content/browser/browser_main_runner.cc:106
    at ../../content/browser/browser_main.cc:22
   from /usr/lib/xwalk/libcontent.so
    at ../../content/app/content_main.cc:19

Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@globallogic.com>