Remove some unused strings.

Remove some unused strings.

These were used to enable the "Other sessions" menu on NTP4.
This UI has already shipped AND been removed.

R=thestig@chromium.org
BUG=none

Committed: https://crrev.com/4ebbf2963cc7d80300b6c1ef019d4bbd0ed18722
Cr-Commit-Position: refs/heads/master@{#341935}

[Lei Zhang, 2015-08-04 23:48:47]

lgtm

[Dan Beam, 2015-08-05 00:32:00]

The CQ bit was checked by dbeam@chromium.org

[commit-bot: I haz the power, 2015-08-05 00:34:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1268433005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1268433005/1

[commit-bot: I haz the power, 2015-08-05 01:48:13]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-05 01:48:13]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[Dan Beam, 2015-08-05 18:12:45]

The CQ bit was checked by dbeam@chromium.org

[commit-bot: I haz the power, 2015-08-05 18:13:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1268433005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1268433005/1

[commit-bot: I haz the power, 2015-08-05 19:12:56]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-05 19:13:44]

Patchset 1 (id:??) landed as
https://crrev.com/4ebbf2963cc7d80300b6c1ef019d4bbd0ed18722
Cr-Commit-Position: refs/heads/master@{#341935}