Register browser in Selenium2Library

foobar.py

from selenium import webdriver
from robot.libraries.BuiltIn import BuiltIn


def open_my_browser(url):
    # Code here to open browser your my way
    driver = webdriver.Chrome()
    # Code here to open browser my way ends
    driver.get(url)
    s2l = BuiltIn().get_library_instance('Selenium2Library')
    s2l._cache.register(driver, None)

foobar.robot

*** Settings ***
Library           foobar.py
Library           Selenium2Library

*** Test Cases ***
Example
    Open My Browser    https://www.google.fi/
    Selenium2Library.Wait Until Page Contains    Google
    Selenium2Library.Close All Browsers