Manual:ContentHandler.php

ContentHandler.php contains the ContentHandler class, the base interface for content handling. This file has been available since MediaWiki 1.21.

Migration
Revision::getRawText was deprecated in MW 1.21, so if you're trying to migrate your code use Revision::getText was deprecated in MW 1.21, so if you're trying to migrate your code use this (see Manual:Revision.php for more info on the different audiences):