Welcome to Android Central! First, try booting into Safe Mode. If the ads go away, then it's probably due to some 3rd party adware that was installed alongside an app.
https://support.t-mobile.com/docs/DOC-11473. You'd have to uninstall apps one by one until the behavior goes away.
Also try clearing all browsing data for Chrome, both on the phone and on your computer, from the beginning of time.
If the ads persist in Safe Mode, then the malware might have been installed to the system root. This can be difficult, since a factory reset won't get rid of it. You could try reinstalling the firmware, using either Kies, Smart Switch, or Odin:
http://forums.androidcentral.com/amb...interface.html