How to resolve this with the latest version of Selenium.
Using NuGet, search for DotNetSeleniumExtras.WaitHelpers, and import that namespace into your class. Now you can do this:
var wait = new WebDriverWait(driver, new TimeSpan(0, 0, 30));
var element = wait.Until(SeleniumExtras.WaitHelpers.ExpectedConditions.ElementIsVisible(By.Id("content-section")));
And the warning in the IDE will be gone.