Enable HistoryModelWorker by default, now that bug 69561 is fixed.

BUG=69561
TEST=Run sync manually and run integration tests, sync should not crash.

Review URL: http://codereview.chromium.org/7016007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@85211 0039d316-1c4b-4281-b951-d872f2087c98
void SyncBackendHost::Core::DoShutdown(bool sync_disabled) {
  DCHECK(MessageLoop::current() == host_->core_thread_.message_loop());

  save_changes_timer_.Stop();
  syncapi_->Shutdown();  // Stops the SyncerThread.
  syncapi_->RemoveObserver(this);
  DisconnectChildJsEventRouter();
  host_->ui_worker()->OnSyncerShutdownComplete();

  if (sync_disabled)
    DeleteSyncDataFolder();

  host_ = NULL;
}

void SyncBackendHost::Core::DoShutdown(bool sync_disabled) {
  DCHECK(MessageLoop::current() == host_->core_thread_.message_loop());

  save_changes_timer_.Stop();
  syncapi_->Shutdown();  // Stops the SyncerThread.
  syncapi_->RemoveObserver(this);
  DisconnectChildJsEventRouter();
  host_->ui_worker()->OnSyncerShutdownComplete();

  if (sync_disabled)
    DeleteSyncDataFolder();

  host_ = NULL;
}
