You can set the background image to an activity by setting android:background xml attributes as followings: (Here, for example, Take a LinearLayout for an activity and setting a background image for the layout(i.e. indirectly to an activity)).
Mobdro is 100% legal in USA. You donât need to worry about it. Up to now, there is no legal issues regarding Mobdro application. Mobdro streaming application is quite familiar to UK and US people.
There is no U.S. federal law against gambling online. There is no U.S. federal law against gambling online. On the federal level, gambling online is perfectly legal, because of the lack of a law against it. It's possible to run afoul of state law (especially in extremely conservative states), but even there prosecution is extremely rare. This article focuses mostly on federal law.