feat(unsupported): provide custom blacklist for branding

react/features/app/getRouteToRender.js

 import type { Component } from 'react';
 
 import { isRoomValid } from '../base/conference';
-import JitsiMeetJS from '../base/lib-jitsi-meet';
-import { Platform } from '../base/react';
 import { toState } from '../base/redux';
+import { isSupportedBrowser } from '../base/environment';
 import { Conference } from '../conference';
 import { getDeepLinkingPage } from '../deep-linking';
 import { UnsupportedDesktopBrowser } from '../unsupported-browser';
         .then(deepLinkComponent => {
             if (deepLinkComponent) {
                 route.component = deepLinkComponent;
-            } else if (_isSupportedBrowser()) {
+            } else if (isSupportedBrowser()) {
                 route.component = Conference;
             } else {
                 route.component = UnsupportedDesktopBrowser;
     const route = _getEmptyRoute();
 
     if (isWelcomePageUserEnabled(state)) {
-        if (_isSupportedBrowser()) {
+        if (isSupportedBrowser()) {
             route.component = WelcomePage;
         } else {
             route.component = UnsupportedDesktopBrowser;
     return Promise.resolve(route);
 }
 
-/**
- * Returns whether or not the current browser should allow the app to display.
- *
- * @returns {boolean}
- */
-function _isSupportedBrowser() {
-    if (navigator.product === 'ReactNative') {
-        return false;
-    }
-
-    // We are intentionally allow mobile browsers because:
-    // - the WelcomePage is mobile ready;
-    // - if the URL points to a conference, getDeepLinkingPage will take
-    //   care of it.
-    return Platform.OS === 'android'
-        || Platform.OS === 'ios'
-        || JitsiMeetJS.isWebRtcSupported();
-}
-
 /**
  * Returns the default {@code Route}.
  *

react/features/base/environment/environment.js

+// @flow
+
+import JitsiMeetJS from '../lib-jitsi-meet';
+import { Platform } from '../react';
+
+import { isBlacklistedEnvironment } from './isBlacklistedEnvironment';
+
+/**
+ * Returns whether or not the current browser should allow the app to display.
+ *
+ * @returns {boolean}
+ */
+export function isSupportedBrowser() {
+    if (navigator.product === 'ReactNative' || isBlacklistedEnvironment()) {
+        return false;
+    }
+
+    // We are intentionally allow mobile browsers because:
+    // - the WelcomePage is mobile ready;
+    // - if the URL points to a conference then deep-linking will take
+    //   care of it.
+    return Platform.OS === 'android'
+        || Platform.OS === 'ios'
+        || JitsiMeetJS.isWebRtcSupported();
+}

react/features/base/environment/index.js

+export * from './environment';

react/features/base/environment/isBlacklistedEnvironment.js

+/**
+ * Returns whether or not the current browser is supported for showing meeting
+ * based on any custom overrides. This file should be overridden with branding
+ * as needed to fit deployment needs.
+ *
+ * @returns {boolean} True the browser is unsupported due to being  blacklisted
+ * by the logic within this function.
+ */
+export function isBlacklistedEnvironment() {
+    return false;
+}