UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.101 Safari/537.36

Steps to reproduce the problem:
1. Run the following F# code:
let chromeOptions = new ChromeOptions(BinaryLocation = _chromium)
chromeOptions.AddArguments
    (
        "--headless", 
        "--disable-gpu"                    
    )
let chrome = new ChromeDriver(chromeOptions, Url = "http://www.example.com")

try                
    Console.WriteLine(chrome.Capabilities.Platform)
    Console.WriteLine(chrome.Capabilities.BrowserName)
    Console.WriteLine(chrome.Capabilities.Version)
    let res = chrome.ExecuteScript("return chrome;")
    Console.WriteLine(res)
with e -> 
    Console.WriteLine(e.Message)

chrome.Quit()

What is the expected behavior?
Starting ChromeDriver 2.31.488763 (092de99f48a300323ecf8c2a4e2e7cab51de5ba8) on port 60248
Only local connections are allowed.
Any
chrome
62.0.3188.0
System.Collections.Generic.Dictionary`2[System.String,System.Object]

What went wrong?
Starting ChromeDriver 2.31.488763 (092de99f48a300323ecf8c2a4e2e7cab51de5ba8) on port 61158
Only local connections are allowed.
Any
chrome
62.0.3188.0
unknown error: chrome is not defined
  (Session info: headless chrome=62.0.3188.0)
  (Driver info: chromedriver=2.31.488763 (092de99f48a300323ecf8c2a4e2e7cab51de5ba8),platform=Windows NT 10.0.15063 x86_64)

Did this work before? No 

Chrome version: 62.0.3188.0  Channel: n/a
OS Version: 10.0
Flash Version: 

This problem arise only when Chrome is launched with the headless option. Without that option it works fine.