I\'m using the code below to start chrome using webdriver (selenium 2)
Map mobileEmulation = new HashMap(
Use below code:-
ChromeOptions options = new ChromeOptions();
options.addExtensions(new File("/path/to/extension.crx"));
DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(ChromeOptions.CAPABILITY, options);
ChromeDriver driver = new ChromeDriver(capabilities);
Hope it will help you :)