rn: show conference subject if set

react/features/base/conference/actions.js

     conference.on(
         JitsiConferenceEvents.CONFERENCE_LEFT,
         (...args) => dispatch(conferenceLeft(conference, ...args)));
+    conference.on(JitsiConferenceEvents.SUBJECT_CHANGED,
+        (...args) => dispatch(conferenceSubjectChanged(...args)));
 
     conference.on(
         JitsiConferenceEvents.KICKED,

react/features/base/conference/functions.js

 // @flow
 
+import _ from 'lodash';
+
 import { JitsiTrackErrors } from '../lib-jitsi-meet';
 import {
     getLocalParticipant,
 export function getConferenceName(stateful: Function | Object): string {
     const state = toState(stateful);
     const { callee } = state['features/base/jwt'];
+    const { callDisplayName } = state['features/base/config'];
+    const { pendingSubjectChange, room, subject } = state['features/base/conference'];
 
-    return state['features/base/config'].callDisplayName
-                || (callee && callee.name)
-                || state['features/base/conference'].room;
+    return pendingSubjectChange || subject || callDisplayName || (callee && callee.name) || _.startCase(room);
 }
 
 /**

react/features/conference/components/native/NavigationBar.js

 // @flow
 
-import _ from 'lodash';
 import React, { Component } from 'react';
 import { SafeAreaView, Text, View } from 'react-native';
 import LinearGradient from 'react-native-linear-gradient';
  */
 function _mapStateToProps(state) {
     return {
-        _meetingName: _.startCase(getConferenceName(state)),
+        _meetingName: getConferenceName(state),
         _visible: isToolboxVisible(state)
     };
 }