Remove TabContents from TabStripModelObserver::TabDetachedAt.

BUG=107201
TEST=no visible change


Review URL: https://chromiumcodereview.appspot.com/11293205

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167122 0039d316-1c4b-4281-b951-d872f2087c98
void PasswordStoreLoginsChangedObserver::RegisterObserversTask() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
  registrar_.reset(new content::NotificationRegistrar);
  registrar_->Add(this, chrome::NOTIFICATION_LOGINS_CHANGED,
                  content::NotificationService::AllSources());
  done_event_.Signal();
}

void PasswordStoreLoginsChangedObserver::RegisterObserversTask() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
  registrar_.reset(new content::NotificationRegistrar);
  registrar_->Add(this, chrome::NOTIFICATION_LOGINS_CHANGED,
                  content::NotificationService::AllSources());
  done_event_.Signal();
}
