With the `2357` branch you can still use `NPAPI` though it's disabled by default.
There is a command line flag to enable it, see
viewtopic.php?f=6&t=13106&p=26358#p26358
See the upstream `Chromium` document for more details on the lifespan of `NPAPI`
https://www.chromium.org/developers/npapi-deprecation
I believe the `CEF` `master` branch is using `Chromium 45` which no longer has `NPAPI` support (Or if it does still have support, expect it to be removed in the near future).