To the OP: Seriously, inform the police, it's a little bit of hassle for you, but as has been said, they will go round to the Dixy chicken and ask for their CCTV, they should comply, as although they are a franchise, they are a big one (can think of at least 2 here in Manchester.) It may take a little while but at the very least, it will have been logged, which gives you more power should anything like that ever happen again.
To those saying the police wont do anything simply because of the OPs skin colour, that's simply rubbish. While you may be right, they may not log it as a hate crime (and whether they should is not as open and shut as you might think), they most certainly want to crack down on gang violence, especially in places like Leeds and Manchester, which already have very bad reps around the country for this sort of thing.
You all make it sound like the police have a tick sheet they use when they receive a call, "is the victim not white? YES/NO, if YES: do something, if NO: say something condescending and hang up." Absolutely and 100% clearly, that is not the case...
Racism toward white folk was always naturally going to happen if you really think about it and how human behaviour works, different cultural beliefs aside, all of us, across the world, work and think in broadly the same way. When a group of people has been persecuted for a very long time, and then laws and social stigma makes that persecution largely go away (on the surface at least), the least intelligent of those groups of people will do things like the OP experienced as they think its some sort of revenge. Clearly, they are wrong, clearly they are simply thugs and idiots. Hence OP, really, report it!