ref(deep-linking): Improve the window loaded detection logic.

react/features/deep-linking/functions.js

     from './shouldShowDeepLinkingDesktopPage';
 
 /**
- * Indicates whether the window load event was already received.
+ * Promise that resolves when the window load event is received.
  *
- * @type {boolean}
+ * @type {Promise<void>}
  */
-let windowIsLoaded = false;
-
-/**
- * Handler for the window load event.
- *
- * @returns {void}
- */
-function onWindowLoad() {
-    windowIsLoaded = true;
-    window.removeEventListener('load', onWindowLoad);
-}
+const windowLoadedPromise = new Promise(resolve => {
+    /**
+     * Handler for the window load event.
+     *
+     * @returns {void}
+     */
+    function onWindowLoad() {
+        resolve();
+        window.removeEventListener('load', onWindowLoad);
+    }
 
-window.addEventListener('load', onWindowLoad);
+    window.addEventListener('load', onWindowLoad);
+});
 
-/**
- * Executes the passed function after the window load event was received.
- *
- * @param {Function} fn - The function that will be executed.
- * @returns {void}
- */
-function executeAfterWindowLoad(fn) {
-    if (windowIsLoaded) {
-        fn();
-    } else {
-        const loadHandler = () => {
-            fn();
-            window.removeEventListener('load', loadHandler);
-        };
-
-        window.addEventListener('load', loadHandler);
-    }
-}
 
 /**
  * Generates a deep linking URL based on the current window URL.
  * @returns {void}
  */
 export function openDesktopApp() {
-    executeAfterWindowLoad(() => {
+    windowLoadedPromise.then(() => {
         // If the code for opening the deep link is executed before the window
         // load event, something with the internal chrome state goes wrong. The
         // result is that no window load event is received which is the cause