Flutter InAppWebview : The camera turns on when I touch anywhere

Everything works fine in my project. But an interesting situation occurs when I want to access the camera. When I click the button the camera is working, but the camera does not display until I touch anywhere on the screen.

Sometimes the camera displaying by itself, but usually I have to touch anywhere on the screen.

How can i fix this problem?

screen video

main.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:permission_handler/permission_handler.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Permission.camera.request();

  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: InAppWebViewPage());
  }
}

class InAppWebViewPage extends StatefulWidget {
  @override
  _InAppWebViewPageState createState() => new _InAppWebViewPageState();
}

class _InAppWebViewPageState extends State<InAppWebViewPage> {
  InAppWebViewController _webViewController;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text("InAppWebView")),
        body: Container(
            child: Column(children: <Widget>[
          Expanded(
            child: Container(
              child: InAppWebView(
                  initialUrlRequest: URLRequest(
                      url: Uri.parse("https://www.healttest.com/app/")),
                  initialOptions: InAppWebViewGroupOptions(
                    crossPlatform: InAppWebViewOptions(
                      mediaPlaybackRequiresUserGesture: false,
                      //    debuggingEnabled: true,
                    ),
                  ),
                  onWebViewCreated: (InAppWebViewController controller) {
                    _webViewController = controller;
                  },
                  androidOnPermissionRequest:
                      (InAppWebViewController controller, String origin,
                          List<String> resources) async {
                    return PermissionRequestResponse(
                        resources: resources,
                        action: PermissionRequestResponseAction.GRANT);
                  }),
            ),
          ),
        ])));
  }
}

androidManifest.xml

  uses-permission android:name="android.permission.INTERNET"
  uses-permission android:name="android.permission.CAMERA" 
  uses-permission android:name="android.permission.VIDEO_CAPTURE" 
  uses-feature android:name="android.hardware.camera" 
  uses-feature android:name="android.hardware.camera.autofocus"