Does MariaDB rely on MySQL code base on ongoing basis?

Hi,
Our company is interested using MariaDB as part of our development and we are totally fine with GPL license. However, as you mentioned it is developed on Oracle's MySQL and with the direction Oracle is heading we are concerned to use MariaDB. So my question is, does MariaDB has any dependency to My SQL on ongoing basis? Or MariaDB copied the MySQL code base one time and developed independently since and no connection to MySQL what so ever.

Please let me know.

Thank you,
Weranga