Is there a reason for why Google+ took half control over YouTube?

[Johnny]

I haven't really found an answer to this particular question since Google doesn't quite give me the correct answer.
Anyways, I am very curious of why it is that Google+ really just randomly took over YouTube, this question has been in my head for nearly Three Days, so I thought I would ask it now, and get my answer.

Notes: I MIGHT tolerate ANY answers you can find from other internet browsers, because after all, my computer's default is google chrome, and when I try to change it to a different search engine, it blocks that search engine from popping up, or it's just there are some coincidental crashs with some of the websites and are just popping up 404 errors. Anyways, ANY answers that come from internet or intellectual knowledge will most likely be accepted.