Delete zombie udp_socket_unittest.

Delete zombie udp_socket_unittest.

This file was deprecated by corresponding apptests and was deleted in
https://codereview.chromium.org/722943004 .

It was accidentally ressurected when moving the network service
source-of-truth to Chromium - we carried over modifications and new
files, but didn't carry over deletions of whole files.

BUG=450356
Committed: https://crrev.com/f74b2a3e0fe3c7b1bbc7ddba186d758147bb298b
Cr-Commit-Position: refs/heads/master@{#314601}

[ppi, 2015-02-04 14:48:05]

Patchset #1 (id:1) has been deleted

[ppi, 2015-02-04 16:41:22]

ppi@chromium.org changed reviewers:
+ jamesr@chromium.org

[ppi, 2015-02-04 16:41:38]

Hi James,

ptal.

[jamesr, 2015-02-04 18:29:55]

lgtm

[ppi, 2015-02-04 18:31:48]

The CQ bit was checked by ppi@chromium.org

[commit-bot: I haz the power, 2015-02-04 18:33:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/894093003/20001

[commit-bot: I haz the power, 2015-02-04 19:09:48]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-02-04 19:12:30]

Patchset 1 (id:??) landed as
https://crrev.com/f74b2a3e0fe3c7b1bbc7ddba186d758147bb298b
Cr-Commit-Position: refs/heads/master@{#314601}