Support WebSocket sub-protocols on Android

[mikemintz]

I rely on the protocols argument in the WebSocket constructor to negotiate the client/server protocol. It looks like it's supported in react-native iOS, but Android appears to be ignoring it.

See WebSocketModule.java line 66

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[sodik82]

+1: I am using STOMP.js over WS and it is working in iOS but not in Android. Most likely the same issue.

[zxcpoiu]

the WebSocketModule.java line 66 says:

// ignoring protocols, since OKHttp overrides them.

related code in okhttp: WebSocketCall.java line 71.

I tried to hard-coded in WebSocketModule.java line 87 with builder.addHeader("Sec-WebSocket-Protocol", "myprotocol");, and it DID add the header Sec-WebSocket-Protocol on the WebSocket handshake. (It did NOT get overridden by OKHttp.)

I tested it on react-native@0.20

Does that mean we can add back the support of websocket sub protocols now?