Fix bugs with ext.flutter.activeDevToolsServerAddress (#74423)

packages/flutter_tools/lib/src/resident_runner.dart

@@ -1420,9 +1420,15 @@ abstract class ResidentRunner {
     } on Exception {
       // do nothing
     }
-    vmService.onExtensionEvent.listen((vm_service.Event event) {
+    StreamSubscription<vm_service.Event> extensionStream;
+    extensionStream = vmService.onExtensionEvent.listen((vm_service.Event event) {
       if (event.json['extensionKind'] == 'Flutter.FrameworkInitialization') {
+        // The 'Flutter.FrameworkInitialization' event is sent on hot restart
+        // as well, so make sure we don't try to complete this twice.
+        if (!completer.isCompleted) {
           completer.complete();
+          extensionStream.cancel();
+        }
       }
     });
     final vm_service.IsolateRef isolateRef = (await vmService.getVM()).isolates.first;

packages/flutter_tools/lib/src/run_hot.dart

@@ -634,6 +634,7 @@ class HotRunner extends ResidentRunner {
       if (!silent) {
         globals.printStatus('Restarted application in ${getElapsedAsMilliseconds(timer.elapsed)}.');
       }
+      unawaited(maybeCallDevToolsUriServiceExtension());
       return result;
     }
     final OperationResult result = await _hotReloadHelper(