What is the default browser of Android 5.0 and above?

Android devices used to have its stock web browser as its default browser, but nowadays, it is replaced by Chrome. And it is said that the default browser of Android 5.0 and above is going to be Chrome. Having said that, what happens if a phone with stock web browser is updated to Android 5.0? Is its stock web browser is deleted as well as replaced by Chrome? Or does it stay as its stock web browser even after the update? If there is any web-site that could support your answer, please attatch its URL as well.

Thanks.