Remove the usbPrivate API.

Remove the usbPrivate API.

This API was to be used by WebUI that enumerates USB devices. This is
being reimplemented as native UI so the API is no longer necessary.

BUG=

Committed: https://crrev.com/9fd4726662eacd649b3071410d5d4c1d5f58c84d
Cr-Commit-Position: refs/heads/master@{#297548}

[Reilly Grant (use Gerrit), 2014-09-30 17:28:31]

reillyg@chromium.org changed reviewers:
+ rockot@chromium.org

[Reilly Grant (use Gerrit), 2014-09-30 17:55:04]

Patchset #1 (id:1) has been deleted

[Reilly Grant (use Gerrit), 2014-09-30 18:01:04]

Patchset #1 (id:20001) has been deleted

[Ken Rockot(use gerrit already), 2014-09-30 18:03:54]

lgtm

[Reilly Grant (use Gerrit), 2014-09-30 22:00:54]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2014-09-30 22:01:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/617933002/40001

[commit-bot: I haz the power, 2014-09-30 22:15:21]

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

[commit-bot: I haz the power, 2014-09-30 22:15:22]

Try jobs failed on following builders:
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[Reilly Grant (use Gerrit), 2014-09-30 23:26:25]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2014-09-30 23:27:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/617933002/80001

[commit-bot: I haz the power, 2014-09-30 23:48:31]

Committed patchset #3 (id:80001) as b4e64871309d9eb47542b39879be9eec4aa2edb0

[commit-bot: I haz the power, 2014-09-30 23:49:05]

Patchset 3 (id:??) landed as
https://crrev.com/9fd4726662eacd649b3071410d5d4c1d5f58c84d
Cr-Commit-Position: refs/heads/master@{#297548}