chrome.sockets.udp API implementations

Yes, Used here: https://github.com/MobileChromeApps/mobile-chrome-apps/blob/32d143209771dc72b91dfed3fed84ef259acbcdf/chrome-cordova/plugins/chrome.sockets.udp/src/ios/ChromeSocketsUdp.m#L195

We can also use a block callback if don't want this be public.