Quick summary of the “disable background data” option on Android
“background data is a suggestion which applications are free to honor or ignore. While you can be sure Google’s core services does honor the flag, I’d be surprised if most third party applications actually do.
Disabling the background data flag also prevents automatic synchronization of Google services (gmail, calendar, contacts) in the background. In fact, I’m not sure if they’ll synchronize at all with that flag disabled. I’ve never actually tried.”