Fix GN build for components/session_manager and /chromeos

Fix GN build for components/session_manager and /chromeos

BUG=None
TEST=user_manager GN ninja build (debug|official; is_component_build=yes|no)
TBR=oshima

Committed: https://crrev.com/8d7d18d60478e740c9bc2423ec5e86e60e72164c
Cr-Commit-Position: refs/heads/master@{#313479}

[Nikita (slow), 2015-01-28 10:11:08]

nkostylev@chromium.org changed reviewers:
+ dpolukhin@chromium.org

[Nikita (slow), 2015-01-28 10:11:09]

omnibox.mojom.js dbg gn build failure is reproduced on TOT and is discussed
separately with sheriffs.

[Dmitry Polukhin, 2015-01-28 10:20:05]

lgtm

[Nikita (slow), 2015-01-28 10:47:42]

The CQ bit was checked by nkostylev@chromium.org

[commit-bot: I haz the power, 2015-01-28 10:48:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/880203003/1

[commit-bot: I haz the power, 2015-01-28 10:53:48]

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

[commit-bot: I haz the power, 2015-01-28 10:53:49]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Nikita (slow), 2015-01-28 11:20:17]

nkostylev@chromium.org changed reviewers:
+ oshima@chromium.org

[Nikita (slow), 2015-01-28 11:20:18]

TBR'ing oshima@ for chromeos/* owners review.

[Nikita (slow), 2015-01-28 11:20:26]

The CQ bit was checked by nkostylev@chromium.org

[commit-bot: I haz the power, 2015-01-28 11:21:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/880203003/1

[commit-bot: I haz the power, 2015-01-28 11:25:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-28 11:26:46]

Patchset 1 (id:??) landed as
https://crrev.com/8d7d18d60478e740c9bc2423ec5e86e60e72164c
Cr-Commit-Position: refs/heads/master@{#313479}