Use req2params middleware for name maps tile endpoint

lib/cartodb/controllers/named_maps.js

@@ -9,6 +9,7 @@ var BaseController = require('./base');
 var cors = require('../middleware/cors');
 var userMiddleware = require('../middleware/user');
 var allowQueryParams = require('../middleware/allow-query-params');
+const req2paramsMiddleware = require('../middleware/req2params-middleware');
 
 function NamedMapsController(authApi, pgConnection, namedMapProviderCache, tileBackend, previewBackend,
                              surrogateKeysCache, tablesExtentApi, metadataBackend) {
@@ -20,6 +21,7 @@ function NamedMapsController(authApi, pgConnection, namedMapProviderCache, tileB
     this.surrogateKeysCache = surrogateKeysCache;
     this.tablesExtentApi = tablesExtentApi;
     this.metadataBackend = metadataBackend;
+    this.req2paramsMiddleware = req2paramsMiddleware(authApi, pgConnection);
 }
 
 util.inherits(NamedMapsController, BaseController);
@@ -27,13 +29,21 @@ util.inherits(NamedMapsController, BaseController);
 module.exports = NamedMapsController;
 
 NamedMapsController.prototype.register = function(app) {
-    app.get(app.base_url_templated +
-        '/:template_id/:layer/:z/:x/:y.(:format)', cors(), userMiddleware,
-        this.tile.bind(this));
+    app.get(
+        app.base_url_templated + '/:template_id/:layer/:z/:x/:y.(:format)',
+        cors(),
+        userMiddleware,
+        this.req2paramsMiddleware,
+        this.tile.bind(this)
+    );
 
-    app.get(app.base_url_mapconfig +
-        '/static/named/:template_id/:width/:height.:format', cors(), userMiddleware, allowQueryParams(['layer']),
-        this.staticMap.bind(this));
+    app.get(
+        app.base_url_mapconfig + '/static/named/:template_id/:width/:height.:format',
+        cors(),
+        userMiddleware,
+        allowQueryParams(['layer']),
+        this.staticMap.bind(this)
+    );
 };
 
 NamedMapsController.prototype.sendResponse = function(req, res, resource, headers, namedMapProvider) {
@@ -81,11 +91,7 @@ NamedMapsController.prototype.tile = function(req, res, next) {
 
     var namedMapProvider;
     step(
-        function reqParams() {
-            self.req2params(req, res, this);
-        },
-        function getNamedMapProvider(err) {
-            assert.ifError(err);
+        function getNamedMapProvider() {
             self.namedMapProviderCache.get(
                 cdbUser,
                 req.params.template_id,