OnePlus One update installs SwiftKey for you. Because.

If you happen to own a OnePlus One, there's an update on the way that's going to bundle in the popular SwiftKey keyboard. Yep, the keyboard you could download for free from the Google Play Store will instead be installed for you (still for free) by an over-the-air update to CyanogenMod 11S.

The update will simply make SwiftKey an option for your typing pleasure on the OnePlus One — it won't be overriding your existing keyboard choice. You'll still have to go to Language and Input in the settings menu to actually switch to the newly-installed SwiftKey. Or you can keep using whatever keyboard you were using before and ignore this bloatware install. Preinstalled apps on the OnePlus One can't be uninstalled, but you can disable it if it really bothers you.

Source: OnePlus