Code:  GLOzone* X11SurfaceFactory::GetGLOzone(gl::GLImplementation implementation) {
   switch (implementation) {
     case gl::kGLImplementationDesktopGL:
       return glx_implementation_.get();
    case gl::kGLImplementationEGLGLES2:
      return egl_implementation_.get();
    default:
      return nullptr;
  }
}

Commit Message: Add ThreadChecker for Ozone X11 GPU.

Ensure Ozone X11 tests the same thread constraints we have in Ozone GBM.

BUG=none

Review-Url: https://codereview.chromium.org/2366643002
Cr-Commit-Position: refs/heads/master@{#421817}
CWE ID: CWE-284
 GLOzone* X11SurfaceFactory::GetGLOzone(gl::GLImplementation implementation) {
  DCHECK(thread_checker_.CalledOnValidThread());
   switch (implementation) {
     case gl::kGLImplementationDesktopGL:
       return glx_implementation_.get();
    case gl::kGLImplementationEGLGLES2:
      return egl_implementation_.get();
    default:
      return nullptr;
  }
}
