What about having:
```
checkForUpdate();
checkForExtensionsUpdate();
window.setInterval(checkForUpdate, ONE_DAY + (2 * 60 * 1000));
```
And move the `setTimeout(checkForExtensionsUpdate, (timeOfNextCheck - currentTime) + 1000);` to `checkForExtensionsUpdate`. Notice that you might need to set the timeout on both instances of the else, the only thing that might change is the time.