transmit: Refactor logic for deferring the socket initialization.

This makes sure that CSRF token is available while initializing
Socket, irrespective of the order of execution of deferred callbacks
after document becomes ready.

This is part of #9416.

frontend_tests/node_tests/transmit.js

@@ -22,6 +22,7 @@ zrequire('people');
 zrequire('transmit');
 
 function test_with_mock_socket(test_params) {
+    transmit.initialize();
     var socket_send_called;
     var send_args = {};
 

static/js/setup.js

@@ -68,5 +68,5 @@ $(function () {
             return $(this).is(sel) || $(this).closest(sel).length;
         };
     }
-
+    transmit.initialize();
 });

static/js/transmit.js

@@ -3,7 +3,7 @@ var transmit = (function () {
 var exports = {};
 
 var socket;
-$(function () {
+exports.initialize =  function () {
     // We initialize the socket inside a function so that this code
     // runs after `csrf_token` is initialized in setup.js.
     if (page_params.use_websockets) {
@@ -11,7 +11,7 @@ $(function () {
     }
     // For debugging.  The socket will eventually move out of this file anyway.
     exports._socket = socket;
-});
+};
 
 function send_message_socket(request, success, error) {
     request.socket_user_agent = navigator.userAgent;