A couple week ago, I was trying to find the best way to try to stroke an animation on a composition, my first guess was to use after effect plug-in which didn’t work so well.
After a while I found out there is a much simpler way just in front on my eyes.

On After Effect CC 2015
– On your After Effect Timeline, Select the composition you would like to stroke
– Click on the Layer tab menu
– Click on Layer Style
– Select Stroke

Done!

It appear to be so easy but I spent a bit of time finding the right solution, hope it helps you!

stroke-composition