It should look like this:
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
options = Options()
options.add_argument('--headless')
options.add_argument('--disable-gpu') # Last I checked this was necessary.
driver = webdriver.Chrome(CHROMEDRIVER_PATH, chrome_options=options)
This works for me using Python 3.6, I’m sure it’ll work for 2.7 too.
Update 2018-10-26: These days you can just do this:
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
options = Options()
options.headless = True
driver = webdriver.Chrome(CHROMEDRIVER_PATH, options=options)