Well, there have been popular apps that have been infected as came pre-installed in phones:
http://thehackernews.com/2015/09/android-smartphone-malware....
As well as apps pulled from Google Play for having malware:
http://www.huffingtonpost.com/2015/02/04/mobile-malware_n_66...
http://www.coindesk.com/google-pulls-six-mobile-wallpaper-ap...
http://fortune.com/2015/07/08/google-play-fake-app/