Revert of Cleanup: Remove base/file_util.h. Convert remaining references.

Revert of Cleanup: Remove base/file_util.h. Convert remaining references. (patchset #1 id:1 of https://codereview.chromium.org/568873004/)

Reason for revert:
Broke some internal builds. Need to give them a chance to fix their builds.

Original issue's description:
> Cleanup: Remove base/file_util.h. Convert remaining references.
>
> TBR=brettw@chromium.org
>
> Committed: https://crrev.com/6d63c4898c2da5a286d01f80229baeb914f99f18
> Cr-Commit-Position: refs/heads/master@{#294729}

TBR=brettw@chromium.org
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/cdf83e8f7ec3d723c058260a492c2d9f83ec4a25
Cr-Commit-Position: refs/heads/master@{#294755}

[Lei Zhang, 2014-09-13 20:58:50]

Created Revert of Cleanup: Remove base/file_util.h. Convert remaining
references.

[commit-bot: I haz the power, 2014-09-13 20:59:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/565803006/1

[commit-bot: I haz the power, 2014-09-13 21:02:13]

Committed patchset #1 (id:1) as d6ec632a254e9837b5d8c4dd780dfe779da05213

[commit-bot: I haz the power, 2014-09-13 21:04:20]

Patchset 1 (id:??) landed as
https://crrev.com/cdf83e8f7ec3d723c058260a492c2d9f83ec4a25
Cr-Commit-Position: refs/heads/master@{#294755}