Add Jitsi screensharing support in electron app

src/vector/platform/ElectronPlatform.js

@@ -21,7 +21,7 @@ import VectorBasePlatform, {updateCheckStatusEnum} from './VectorBasePlatform';
 import dis from 'matrix-react-sdk/lib/dispatcher';
 import { _t } from 'matrix-react-sdk/lib/languageHandler';
 import Promise from 'bluebird';
-import {remote, ipcRenderer} from 'electron';
+import {remote, ipcRenderer, desktopCapturer} from 'electron';
 import rageshake from '../rageshake';
 
 remote.autoUpdater.on('update-downloaded', onUpdateDownloaded);
@@ -207,4 +207,43 @@ export default class ElectronPlatform extends VectorBasePlatform {
     reload() {
         remote.getCurrentWebContents().reload();
     }
+
+    /* BEGIN copied and slightly-modified code
+     * setupScreenSharingForIframe function from:
+     * https://github.com/jitsi/jitsi-meet-electron-utils
+     * Copied directly here to avoid the need for a native electron module for
+     * 'just a bit of JavaScript'
+     * NOTE: Apache v2.0 licensed
+     */
+    setupScreenSharingForIframe(iframe: Object) {
+        iframe.contentWindow.JitsiMeetElectron = {
+            /**
+             * Get sources available for screensharing. The callback is invoked
+             * with an array of DesktopCapturerSources.
+             *
+             * @param {Function} callback - The success callback.
+             * @param {Function} errorCallback - The callback for errors.
+             * @param {Object} options - Configuration for getting sources.
+             * @param {Array} options.types - Specify the desktop source types
+             * to get, with valid sources being "window" and "screen".
+             * @param {Object} options.thumbnailSize - Specify how big the
+             * preview images for the sources should be. The valid keys are
+             * height and width, e.g. { height: number, width: number}. By
+             * default electron will return images with height and width of
+             * 150px.
+             */
+            obtainDesktopStreams(callback, errorCallback, options = {}) {
+                desktopCapturer.getSources(options,
+                    (error, sources) => {
+                        if (error) {
+                            errorCallback(error);
+                            return;
+                        }
+
+                        callback(sources);
+                    });
+            },
+        };
+    }
+    /* END of copied and slightly-modified code */
 }