flutter - How to do a task after user open push notif message (FCM)

I have firebase cloud messaging (FCM) and can send a message to my user.

However, I want to make a scenario that if my user taps notification message on their mobile phone, then the apps will open a view or pop up and do some background task.

is this possible?

Thank You

===Update Question as suggested by Shady Boshra

1) I create google cloud function's firebase using typeScript:

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
admin.initializeApp();
const fcm = admin.messaging();

export const sendNotif = functions.https.onRequest((request, response) => {

   const tokens = request.query.tokens;
   const payload: admin.messaging.MessagingPayload = {
   notification: {
      title: '[TEST-123] title...',
      body: `[TEST-123]  body of message... `,          
      click_action: 'FLUTTER_NOTIFICATION_CLICK',
      tag: "news",
      data: "{ picture: 'https://i.imgur.com/bY2bBGN.jpg', link: 'https://example.com' }"
    }
  };
  const res = fcm.sendToDevice(tokens, payload);
  response.send(res);
});

2) I update my Mobile Apps Code / Dart :

_firebaseMessaging.configure(
onMessage: (Map<String, dynamic> message) {
  print("::==>onMessage: $message");

  message.forEach((k,v) => print("${k} - ${v}"));

  String link = "https://example.com";

  FlutterWebBrowser.openWebPage(url: link, androidToolbarColor: Pigment.fromString(UIData.primaryColor));
  return null;
},

then i try to send push notif when apps is in opened mode.

However, when i try to debug it, i cant find the content of data. it give return below response:

I/flutter (30602): ::==>onMessage: {notification: {body: [TEST-123] body of message... , title: [TEST-123] title...}, data: {}}

I/flutter (30602): ::==>onMessage: {notification: {body: [TEST-123] body of message... , title: [TEST-123] title...}, data: {}}

I/flutter (30602): notification - {body: [TEST-123] body of message... , title: [TEST-123] title...}

I/flutter (30602): data - {}

I/flutter (30602): notification - {body: [TEST-123] body of message... , title: [TEST-123] title...}

I/flutter (30602): data - {}

as you can see, the content of data is blank.

===Update 2

If I edit data by removing double quotes, it return error when running firebase deploy:

> functions@ build /Users/annixercode/myPrj/backend/firebase/functions
> tsc

src/index.ts:10:4 - error TS2322: Type '{ title: string; body: string; click_action: string; tag: string; data: { picture: string; link: string; }; }' is not assignable to type 'NotificationMessagePayload'.
  Property 'data' is incompatible with index signature.
    Type '{ picture: string; link: string; }' is not assignable to type 'string'.

10    notification: {
      ~~~~~~~~~~~~

  node_modules/firebase-admin/lib/index.d.ts:4246:5
    4246     notification?: admin.messaging.NotificationMessagePayload;
             ~~~~~~~~~~~~
    The expected type comes from property 'notification' which is declared here on type 'MessagingPayload'


Found 1 error.

npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! functions@ build: `tsc`
npm ERR! Exit status 2
npm ERR! 
npm ERR! Failed at the functions@ build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/anunixercode/.npm/_logs/2019-08-28T01_02_37_628Z-debug.log

Error: functions predeploy error: Command terminated with non-zero exit code2

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