Revert 221035 "Revert 219146 "[sync] Force re-auth during sync s..."

Revert 221035 "Revert 219146 "[sync] Force re-auth during sync s..."

Restoring the change. Verified that this was not the cause of bug 278543.

> Revert 219146 "[sync] Force re-auth during sync setup if Oauth2 ..."
> 
> > [sync] Force re-auth during sync setup if Oauth2 token is unavailable
> > 
> > If an enterprise user disables sync via a dashboard clear, and goes on
> > to re-enable sync at a later time, set up can fail due to an expired or
> > missing Oauth2 token.
> > 
> > This patch updates SyncSetupHandler::OpenSyncSetup to first check if an
> > auth token is available for sync, and if not, force a re-auth.
> > 
> > R=atwilson
> > TBR=fgorski,rogerta
> > BUG=276650
> > TEST=Disable sync for an enterprise user, exit chrome, delete "Web
> > Data*" from the profile dir, restart chrome, and set up sync. Re-auth
> > must be forced in this case.
> > 
> > Review URL: https://chromiumcodereview.appspot.com/23005016
> 
> TBR=rsimha@chromium.org
> 
> Review URL: https://codereview.chromium.org/23759003

TBR=sail@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=221740

[sail, 2013-09-06 18:30:51]

Committed patchset #1 manually as r221740.

[Raghu Simha, 2013-09-06 22:31:30]

LGTM. Thanks for the re-revert.