Undesired download of Baidu Browser
I'm using LBE Security Manager for a while now (as the "lite version", LBE Privacy Guard, is no longer continued and soesn't work with Android 4.1 and above). I first felt it a bit, umm, over-loaded – but it runs decently (no battery drain or performance issues), and after disabling half of its features I don't need, I'm pretty satisfied with it.

While my primary taget was its privacy protection (revoking app permissions), LBE-SM ships with a load of other features. One of them watches over app installs, and places a note in your notification area when one happened. You then can follow that (tap the notification), and blacklist the app. LBE-SM then blocks all future installations of it.

There are a bunch of additional features, many of them primarily targeted at the Chinese market (cloud anti-virus, call blocker, etc), a basic firewall (block internet-access per app and interface, i.e. separately for WiFi and mobile data), plus more.

It's a closed-source app of Chinese origin, which might sound suspect at first. But there's a huge follow-ship at XDA (and Xposed, and elsewhere), so it can't be that bad ;) Unfortunately, the app version available at Google Play is Chinese only (you won't be able to understand a thing if you're not used to Chinese). But there are ways, like localized English, Vietnamese, German, and other language's versions at XDA - or the LBE Xposed Module to be used with the playstore version, to get a usable installation. I'm using the linked English variant from XDA for a while, and already found it updated a couple of times.