Support was removed from Chrome for NPAPI, which in turn was relied upon by the old Unity Web Player. Unity 5 introduced WebGL as a build option. According to the documentation games built using this should run in most browsers.
Specifically for Chrome, version 43 upwards should work I believe. Be sure to check the documentation though, as there are some settings that may need to be changed in order to run games on your local machine in this way if you just browse to the index.html file created… if you use Build and Run… is shouldn’t be an issue.