[RN] Load config.js with ?room=

In order to load the configuration from the shard that will actually
host the conference, it's imperative that we add the room= query
parameter:

https://meet.jit.si/config.js?room=example

This implies a departure from our current model, where the config is
discarded if the domain for the next conference is different, but kept
otherwise.

react/features/app/actions.js

 function _appNavigateToMandatoryLocation(
         dispatch: Dispatch<*>, getState: Function,
         newLocation: Object) {
-    const oldLocationURL = getState()['features/base/connection'].locationURL;
-    const oldHost = oldLocationURL ? oldLocationURL.host : undefined;
-    const newHost = newLocation.host;
-
-    if (oldHost === newHost) {
-        dispatchSetLocationURL()
-            .then(dispatchSetRoom);
-    } else {
-        // If the host has changed, we need to load the config of the new host
-        // and set it, and only after that we can navigate to a different route.
-        _loadConfig(newLocation)
-            .then(
-                config => configLoaded(/* err */ undefined, config),
-                err => configLoaded(err, /* config */ undefined))
-            .then(dispatchSetRoom);
-    }
+    _loadConfig(newLocation)
+        .then(
+            config => configLoaded(/* err */ undefined, config),
+            err => configLoaded(err, /* config */ undefined))
+        .then(() => dispatch(setRoom(newLocation.room)));
 
     /**
      * Notifies that an attempt to load a config(uration) has completed. Due to
         }
 
         return (
-            dispatchSetLocationURL()
+            dispatch(setLocationURL(new URL(newLocation.toString())))
                 .then(() => dispatch(setConfig(config))));
     }
-
-    /**
-     * Dispatches {@link setLocationURL} in the redux store.
-     *
-     * @returns {void}
-     */
-    function dispatchSetLocationURL() {
-        return dispatch(setLocationURL(new URL(newLocation.toString())));
-    }
-
-    /**
-     * Dispatches {@link _setRoomAndNavigate} in the redux store.
-     *
-     * @returns {void}
-     */
-    function dispatchSetRoom() {
-        return dispatch(setRoom(newLocation.room));
-    }
 }
 
 /**
  * @private
  * @returns {Promise<Object>}
  */
-function _loadConfig(location: Object) {
-    let protocol = location.protocol.toLowerCase();
+function _loadConfig({ contextRoot, host, protocol, room }) {
+    /* eslint-disable no-param-reassign */
+
+    protocol = protocol.toLowerCase();
 
     // The React Native app supports an app-specific scheme which is sure to not
     // be supported by fetch (or whatever loadConfig utilizes).
 
     // TDOO userinfo
 
-    return (
-        loadConfig(
-            `${protocol}//${location.host}${location.contextRoot || '/'}`));
+    let url = `${protocol}//${host}${contextRoot || '/'}config.js`;
+
+    // XXX In order to support multiple shards, tell the room to the deployment.
+    room && (url += `?room=${room.toLowerCase()}`);
+
+    /* eslint-enable no-param-reassign */
+
+    return loadConfig(url);
 }

react/features/base/lib-jitsi-meet/functions.js

 /**
  * Loads config.js from a specific remote server.
  *
- * @param {string} host - Host where config.js is hosted.
- * @param {string} path='config.js' - Relative pah to config.js file.
+ * @param {string} url - The URL to load.
  * @returns {Promise<Object>}
  */
-export function loadConfig(host: string, path: string = 'config.js') {
+export function loadConfig(url: string) {
     let promise;
 
     if (typeof APP === 'undefined') {
         promise
-            = loadScript(new URL(path, host).toString())
+            = loadScript(url)
                 .then(() => {
                     const { config } = window;
 
                     return config;
                 })
                 .catch(err => {
-                    console.error(`Failed to load ${path} from ${host}`, err);
+                    console.error(`Failed to load config from ${url}`, err);
 
                     throw err;
                 });