Author: Ankit Agarwal
MDL-40052 events: Add a base class for content view
http://git.moodle.org/gw?p=moodle.git;a=commit;h=589748316dac29ee2050bc29171133feef9f99e2
http://github.com/moodle/moodle/commit/589748316dac29ee2050bc29171133feef9f99e2
+ 2.6 en [eventcontentviewed,core]