I have Chrome and also Chromium and since installing they've not been
used much - not a fan of Chrome. However, since the Chrome PPA is in
my updates sources I get regular updates through the usual Ubuntu
Update Manager. Perhaps if the PPA isn't there the browser would show
an update is there to apply but if the user chooses not to apply, or
doesn't notice / understand the change in the wrench icon, then it
doesn't update. Having the PPA means that updates install without any
user interaction other than getting the usual Ubuntu updates.