Compile File Manager Private API on Chrome OS only.

Compile File Manager Private API on Chrome OS only.

This API is used on Chrome OS only. No need to compile the schema on all
operating systems.

TEST=All current Files app tests pass.
BUG=None

Committed: https://crrev.com/da67bae38f2a912e67b4dd3eb1554b49d620156f
Cr-Commit-Position: refs/heads/master@{#326821}

[mtomasz, 2015-04-24 12:51:07]

mtomasz@chromium.org changed reviewers:
+ kalman@chromium.org

[mtomasz, 2015-04-24 12:51:14]

@kalman: PTAL. Thanks.

[not at google - send to devlin, 2015-04-24 16:40:08]

lgtm

[mtomasz, 2015-04-24 17:01:42]

The CQ bit was checked by mtomasz@chromium.org

[commit-bot: I haz the power, 2015-04-24 17:02:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1093923006/1

[commit-bot: I haz the power, 2015-04-24 17:05:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-24 17:06:47]

Patchset 1 (id:??) landed as
https://crrev.com/da67bae38f2a912e67b4dd3eb1554b49d620156f
Cr-Commit-Position: refs/heads/master@{#326821}