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.

Start by comparing the service's onMessage setup with the onBackgroundMessage registration in firebase-messaging-sw.js, then reproduce the behavior with the PWA in the background. Done means the expected handler is established and the notification tap behavior is corrected or the limitation is clearly documented.

Written by the indexing model from the issue text.