Steps to reproduce the problem:
This has to do with Background sync (and I don't think any other browser supports it at all, that's why it's "just a Chromium problem). I am testing it on an Android tablet that has both Cellular and WiFi access, and test by toggling WiFi on and off (when WiFi is disabled the connection moves to cellular and the other way around), and also by (when connected to WiFi) connecting to another WiFi network.

All code is in the ServiceWorker, and the basic functionality is to a) listen to navigator.connection "typechange" events, and when that happens b) register to send a report to the server on "sync" event.

The core parts look something like (all in the ServiceWorker):

self.addEventListener('sync', (evt) => {
    console.log('SW sync event fired, event tag: ' + evt.tag);
    if (evt.tag == 'send_client_status_reports') {
        evt.waitUntil(sendClientReports());
    }
});
navigator.connection.addEventListener('typechange', networkChangeHandler);

function networkChangeHandler() {
    collectClientStatus().then(() => {
        console.log('gonna register for sending on sync event');
        // If we're online the event should fire immediately
        self.registration.sync.register('send_client_status_reports').then(() => {
            console.log('sync registration success');
        }).catch(e => {
            console.log('sync registation failed, error: ' + e);
        });
    })
    .catch(error => {
        logger.error(`Could not collectClientStatus ${error}\n${error.stack}`);
    });
}

function sendClientReports() {
   // basically just sends off the report created by collectClientStatus using
   // fetch with method 'POST'
   // and returns a Promise that is resolved if the POST is successful and rejected otherwise
}

What is the expected behavior?
When the 'typechange' event fires, it is (to me) expected that the 'sync' event would not fire until there is a working connection up.

What went wrong?
This is what I typically see:

Case 1: wifi -> cellular
------------------------
1. navigator.connection fires "typechange" (type: "none")
2. script registers to send report with on "sync" event
3. "sync" event fires immediately but sending (of course) fails (since 
network is "none")
4. navigator.connection fires another "typechange" (type: "cellular")
5. script registers to send reports with on "sync" event
---- time passes ----
6. "sync" event fires again and reports are sent.

Case 2: cellular -> wifi
------------------------
1. navigator.connection fires "typechange" (type: "wifi")
2. script registers to send report with on "sync" event
3. "sync" event fires immediately but sending fails
---- time passes ----
4. "sync" event fires again and report is sent.

Case 3: wifi -> wifi
--------------------
This is quite similar to Case 1, with the following additional steps 
between 5. and 6:
5.1. navigator.connection fires "typechange" (type: "wifi")
5.2. script registers to send report with on "sync" event

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 57.0.2950.3  Channel: n/a
OS Version: 6.0.1
Flash Version: -

There seems to be some kind of race condition, sometimes things just work (I assume then the new connection is able to get up quickly enough to be able to send