I've just successfully integrated the C++ version of Google Play Game Services into my Cocos2d-x project, at least as far as the compiler is concerned. I've been working from Chukong's experimental project Wagon War. My project compiles without error, including a call to gps::GamesServices::StartAuthorizationUI() through the BeginUserInitiatedSignIn() method of Chukong's wrapper class, GPGSManager.
StartAuthorizationUI(), however, does nothing. I've tried calling it before, after, and instead of running my main scene to see if my UI is covering up Google's UI, and that's not the problem. StartAuthorizationUI() definitely gets called, but nothing happens. I've set up my app on the Google Developer Console and put my app ID in the same place Chukong put his, and no luck. StartAuthorizationUI() runs and exits without error, but nothing happens. My game just does what it's always done with no authorization UI in sight.
Any ideas? I haven't quite been able to get Wagon War itself to run, which might be helpful, but I don't see Chukong doing any setup before he calls StartAuthorizationUI() that I'm not doing before I call it. What am I missing?