[Sync] Cleanup all tab sync enabling logic now that its on by default.

BUG=none
TEST=


Review URL: https://chromiumcodereview.appspot.com/10443046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@139462 0039d316-1c4b-4281-b951-d872f2087c98
void ProfileSyncService::OnSyncManagedPrefChange(bool is_sync_managed) {
  NotifyObservers();
  if (is_sync_managed) {
    DisableForUser();
  } else if (HasSyncSetupCompleted() &&
             IsSyncEnabledAndLoggedIn() &&
             IsSyncTokenAvailable()) {
    StartUp();
  }
}

void ProfileSyncService::OnSyncManagedPrefChange(bool is_sync_managed) {
  NotifyObservers();
  if (is_sync_managed) {
    DisableForUser();
  } else if (HasSyncSetupCompleted() &&
             IsSyncEnabledAndLoggedIn() &&
             IsSyncTokenAvailable()) {
    StartUp();
  }
}
