fix(dropbox): OAuth to use postMessage.

react/features/dropbox/functions.web.js

 
 import { Dropbox, DropboxAuth } from 'dropbox';
 
-import { getJitsiMeetGlobalNS } from '../base/util';
-
 /**
  * Executes the oauth flow.
  *
  */
 function authorize(authUrl: string): Promise<string> {
     const windowName = `oauth${Date.now()}`;
-    const gloabalNS = getJitsiMeetGlobalNS();
-
-    gloabalNS.oauthCallbacks = gloabalNS.oauthCallbacks || {};
 
     return new Promise(resolve => {
-        const popup = window.open(authUrl, windowName);
-
-        gloabalNS.oauthCallbacks[windowName] = url => {
-            popup.close();
-            delete gloabalNS.oauthCallbacks.windowName;
-            resolve(url);
+        // eslint-disable-next-line prefer-const
+        let popup;
+        const handleAuth = ({ data }) => {
+            if (data && data.type === 'dropbox-login' && data.windowName === windowName) {
+                if (popup) {
+                    popup.close();
+                }
+                window.removeEventListener('message', handleAuth);
+                resolve(data.url);
+            }
         };
+
+        window.addEventListener('message', handleAuth);
+        popup = window.open(authUrl, windowName);
     });
 }
 

static/oauth.html

     <script>
         (function() {
             var windowName = window.name;
-            var parentWindow = window.opener;
-            if (parentWindow
-                && parentWindow.JitsiMeetJS
-                && parentWindow.JitsiMeetJS.app) {
-                var globalNS = parentWindow.JitsiMeetJS.app;
-                if (globalNS.oauthCallbacks
-                    && typeof globalNS.oauthCallbacks[windowName]
-                        === 'function') {
-                    globalNS.oauthCallbacks[windowName](window.location.href);
-                }
-            }
+            window.opener && window.opener.postMessage({
+                type: 'dropbox-login',
+                windowName,
+                url: window.location.href
+            }, window.location.origin);
         })();
     </script>
 </head>