Unable to send sendBroadcast from SyncAdapter to Activity

I have an application with a SyncAdapter that runs fine. The SyncService runs once per hour.

My application has a main FragmentActivity called DeviceControlActivity and I would like to receive messages from the SyncAdaptor, such as the syncResult.

I've tried a lot to get it up and running, but I'm not able to receive any messages on DeviceControlActivity from SyncAdapter.

In my DeviceControlActivity I do:

private BroadcastReceiver mSyncMessageReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d(TAG, "Got it!");
    }
};

@Override
protected void onResume() {
    super.onResume();
    // Receive feedback from syncManager
    LocalBroadcastManager.getInstance(getApplication()).registerReceiver(mSyncMessageReceiver,
            new IntentFilter(Constants.MESSAGE_SYNC));
}

@Override
protected void onPause() {
    super.onPause();
    LocalBroadcastManager.getInstance(this).unregisterReceiver(mSyncMessageReceiver);
}

On the SyncAdapter, I have:

private LocalBroadcastManager mBroadcastManager;

public SyncAdapter(Context context, boolean autoInitialize) {
    super(context, autoInitialize);


    mBroadcastManager = LocalBroadcastManager.getInstance(context);
}

@Override
public void onPerformSync(
        Account account,
        Bundle extras,
        String authority,
        ContentProviderClient provider,
        SyncResult syncResult) {

    Intent intent = new Intent(Constants.MESSAGE_SYNC);
    mBroadcastManager.sendBroadcast(intent);

I can send messages from DeviceControlActivity to itself and it works.

I can receive messages from the SyncService, but using an alternative way:

final int mask = ContentResolver.SYNC_OBSERVER_TYPE_PENDING | ContentResolver.SYNC_OBSERVER_TYPE_ACTIVE;
mSyncMonitor = ContentResolver.addStatusChangeListener(mask, this);

This listener reports the sync activity as expected.

But I would like to use a LocalBroadcastManager to communicate between the Service and the Activity, but I'm not able.

I've already check related questions like How to use LocalBroadcastManager?

According to the LocalBroadcastManager documentation this class is a Helper to register for and send broadcasts of Intents to local objects within your process.

The above example dos not work if the <service> runs on a different process.

The AndroidManifest.xml was:

<service
            android:name=".sync.SyncService"
            android:exported="true"
            android:process=":sync">

This is the way suggested in Creating a Sync Adapter.

If we change the <service> declaration to:

    <service
        android:name=".sync.SyncService"
        android:exported="true">

removing the android:process property, the SyncServicewill run in the same process and the LocalBroadcastManager will work.