When pwa is in background, the serviceworker still uses onMessage not onBackgroundMessage!

Hello,

when I send a push notification to my app, the onMessage method is called even if it is in the background! Actually, the onBackgroundMessage should then be called, right? The problem now is that when I tap on the message box in Android, the Progressive Web Application is not brought to the foreground. Apparently Android thinks that the app is in the foreground? The message box disappears when I tap on it and the number of incoming messages also disappears from the app icon.

Is there any way to fix this?

The onMessage is defined in a service
`this.message$ = new Observable(sub => onMessage(this.messaging, it => sub.next(it))).pipe(
tap(payload => {this.print.info('MessagingService initFCMMessaging() FCM fmessage', { payload });})
);`

The onBackgroundMessage is defined in the firebase-messaging-sw.js with static text.

`messaging.onBackgroundMessage(function(payload) {
// Customize notification here
const notificationTitle = 'My title';
const notificationOptions = {
body: 'My Bodytext',
icon: '/firebase-logo.png' || '/assets/icons/icon-72x72.png'
};

self.registration.showNotification(notificationTitle, notificationOptions);
});`

I only noticed this because I defined a static text for the background message.

Comienza comparando la configuración de onMessage del servicio con el registro de onBackgroundMessage en firebase-messaging-sw.js y, a continuación, reproduce el comportamiento con la PWA en segundo plano. Se considera terminado cuando el handler esperado está establecido y el comportamiento al tocar la notificación se ha corregido o la limitación está claramente documentada.

Escrito por el modelo de indexación a partir del texto del issue.