Fix mirror sender and use getDisplayMedia

ext/src/global.d.ts

@@ -29,13 +29,17 @@ declare interface HTMLCanvasElement {
 }
 
 declare interface MediaTrackConstraints {
-    mediaSource: "screen" | "window";
+    cursor: "always" | "motion" | "never";
 }
 
 declare interface RTCPeerConnection {
     addStream (mediaStream: MediaStream): void;
 }
 
+declare interface MediaDevices {
+     getDisplayMedia(constraints: MediaStreamConstraints): Promise<MediaStream>;
+}
+
 
 interface CloneIntoOptions {
     cloneFunctions?: boolean;