Начал разбираться с вызовом специфичной для андроида Activity

android/app/src/main/AndroidManifest.xml

@@ -28,5 +28,8 @@
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
+
+        <activity android:name=".CameraActivity"
+                  android:theme="@android:style/Theme.Black.NoTitleBar"/>
     </application>
 </manifest>

android/app/src/main/java/com/yourcompany/checker/CameraActivity.java

@@ -0,0 +1,17 @@
+package com.yourcompany.checker;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.os.Bundle;
+
+import com.yourcompany.checker.R;
+
+public class CameraActivity extends Activity {
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.a_scanner);
+    }
+
+}

android/app/src/main/java/com/yourcompany/checker/MainActivity.java

@@ -1,14 +1,38 @@
 package com.yourcompany.checker;
 
 import android.os.Bundle;
+import android.content.Intent;
+import android.util.Log;
+import com.yourcompany.checker.CameraActivity;
 
 import io.flutter.app.FlutterActivity;
 import io.flutter.plugins.GeneratedPluginRegistrant;
 
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel;
+import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
+import io.flutter.plugin.common.MethodChannel.Result;
+
 public class MainActivity extends FlutterActivity {
-  @Override
-  protected void onCreate(Bundle savedInstanceState) {
-    super.onCreate(savedInstanceState);
-    GeneratedPluginRegistrant.registerWith(this);
-  }
+
+    private static final String CHANNEL = "samples.flutter.io/battery";
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        GeneratedPluginRegistrant.registerWith(this);
+        new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
+                new MethodCallHandler() {
+                    @Override
+                    public void onMethodCall(MethodCall call, Result result) {
+
+                    }
+                });
+    }
+
+    public void startScanner() {
+        Log.d("kifio", "Start scanner");
+        startActivity(new Intent(MainActivity.this, CameraActivity.class));
+    }
+
 }

android/app/src/main/res/layout/a_scanner.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                xmlns:app="http://schemas.android.com/apk/res-auto"
+                android:id="@+id/rootLayout"
+                android:background="@android:color/white"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"/>

lib/main.dart

@@ -1,4 +1,7 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 
 const String _name = "Ivan Murashov";
 
@@ -18,6 +21,7 @@ class ChatScreen extends StatefulWidget {
 
 class ChatScreenState extends State<ChatScreen> {
 
+  static const platform = const MethodChannel('samples.flutter.io/battery');
   final List<ChatMessage> _messages = <ChatMessage>[];
   final TextEditingController _textController = new TextEditingController();
 
@@ -64,10 +68,19 @@ class ChatScreenState extends State<ChatScreen> {
                                         decoration: textField)),
       new Container(margin: new EdgeInsets.symmetric(horizontal: 4.0),
                     child: new IconButton(icon: new Icon(Icons.send),
-                    onPressed: () => _handleSubmitted(_textController.text)))
+                    onPressed: () => startScanner()))
+//                    onPressed: () => _handleSubmitted(_textController.text)))
     ]);
   }
 
+  Future<Null> startScanner() async {
+    try {
+      platform.invokeMethod('startScanner');
+    } on PlatformException catch (e) {
+
+    }
+  }
+
   void _handleSubmitted(String text) {
     _textController.clear();
     ChatMessage message = new ChatMessage(text);