Silence a warning in unit tests

Silence a warning in generate_policy_source_unittest.cc.

For non-CrOS, compiler gives warning regarding unused functions.

BUG=NONE

Committed: https://crrev.com/3d6b1ddbbc2b0f4f541b433f6c33bb64d4246812
Cr-Commit-Position: refs/heads/master@{#291680}

[binjin, 2014-08-25 12:44:33]

Hello Joao,

Could you have a quick look at this?

bjin

[Joao da Silva, 2014-08-25 12:53:16]

lgtm

[binjin, 2014-08-25 13:06:11]

The CQ bit was checked by binjin@chromium.org

[commit-bot: I haz the power, 2014-08-25 13:07:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/binjin@chromium.org/504723003/1

[commit-bot: I haz the power, 2014-08-25 14:01:11]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_chromium_rel_swarming on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[commit-bot: I haz the power, 2014-08-25 14:39:11]

Committed patchset #1 (1) as 562eba68fd09909257e05a08fb9a9d2258f6d7bc

[commit-bot: I haz the power, 2014-09-10 02:34:27]

Patchset 1 (id:??) landed as
https://crrev.com/3d6b1ddbbc2b0f4f541b433f6c33bb64d4246812
Cr-Commit-Position: refs/heads/master@{#291680}