Don't attempt to revoke old refresh token on reauth.

Don't attempt to revoke old refresh token on reauth.
Since refresh tokens are now tagged with device id, this will invalidate the
new refresh token as well.

BUG=398971
Committed: https://crrev.com/f1f953d6ed8571724e9171efb4a1a2f6a4fe8d57
Cr-Commit-Position: refs/heads/master@{#330096}

[Roger Tawa OOO till Jul 10th, 2015-05-14 21:41:37]

rogerta@chromium.org changed reviewers:
+ mlerman@chromium.org

[Roger Tawa OOO till Jul 10th, 2015-05-14 21:41:37]

Hi Mike,

Please take a look.  Thanks.

[Mike Lerman, 2015-05-15 13:52:48]

Thanks for the offline discussion, to help me catch up :) lgtm!

[Roger Tawa OOO till Jul 10th, 2015-05-15 14:29:44]

The CQ bit was checked by rogerta@chromium.org

[Roger Tawa OOO till Jul 10th, 2015-05-15 14:29:49]

The CQ bit was unchecked by rogerta@chromium.org

[Roger Tawa OOO till Jul 10th, 2015-05-15 14:30:09]

The CQ bit was checked by rogerta@chromium.org

[commit-bot: I haz the power, 2015-05-15 14:30:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129903006/1

[commit-bot: I haz the power, 2015-05-15 15:11:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-15 15:12:44]

Patchset 1 (id:??) landed as
https://crrev.com/f1f953d6ed8571724e9171efb4a1a2f6a4fe8d57
Cr-Commit-Position: refs/heads/master@{#330096}