Cancel notification on remove application from multitask panel

Killing Notifications when main app has been killed.

Since your notification and your app are handled in different threads killing your app via MultitaskManager won’t kill your notification. As you already correctly investigated killing your app won’t even necesarrily result in an onExit() callback.

So what is the solutions?

You could start a service from your activity. A specialty services have: they restart themselves automatically if app-process have been killed for some reason. So you could reuse the automatic restart by killing the notification on restart.

Step 1 create a service that kills
Simple one. It just kills a notification on create and has his special Binder.

public class KillNotificationsService extends Service {

    public class KillBinder extends Binder {
        public final Service service;

        public KillBinder(Service service) {
            this.service = service;
        }

    }

    public static int NOTIFICATION_ID = 666;
    private NotificationManager mNM;
    private final IBinder mBinder = new KillBinder(this);

    @Override
    public IBinder onBind(Intent intent) {
            return mBinder;
    }
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
            return Service.START_STICKY;
    }
    @Override
    public void onCreate() {
            mNM = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            mNM.cancel(NOTIFICATION_ID);
    }
}

Step2: Add it to your manifest:
Add it somewhere inbetween your <application> tags.

<service android:name="KillNotificationsService"></service>

Step3: Always create the Service before fireing the notification, and use the static notificationid.

ServiceConnection mConnection = new ServiceConnection() {
    public void onServiceConnected(ComponentName className,
            IBinder binder) {
        ((KillBinder) binder).service.startService(new Intent(
                MainActivity.this, KillNotificationsService.class));
        Notification notification = new Notification(
                R.drawable.ic_launcher, "Text",
                System.currentTimeMillis());
        Intent notificationIntent = new Intent(MainActivity.this,
                Place.class);
        PendingIntent contentIntent = PendingIntent.getActivity(
                MainActivity.this, 0, notificationIntent, 0);
        notification.setLatestEventInfo(getApplicationContext(),
                "Text", "Text", contentIntent);
        NotificationManager mNM = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        mNM.notify(KillNotificationsService.NOTIFICATION_ID,
                notification);
    }

    public void onServiceDisconnected(ComponentName className) {
    }

};
bindService(new Intent(MainActivity.this,
        KillNotificationsService.class), mConnection,
        Context.BIND_AUTO_CREATE);

It might take a little time until service is restarted (1-5 sec), but it will eventually start and kill the notification.