Revert of [fsp] Add an initial AsyncFileUtil.

Revert of [fsp] Add an initial AsyncFileUtil. (https://codereview.chromium.org/236303017/)

Reason for revert:
Broke Linux Chromium OS Tests -- looks like the new tests aren't working properly there.

Failing build: http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/30018

Original issue's description:
> [fsp] Add an initial AsyncFileUtil.
> 
> This patch adds the AsyncFileUtil implementation for the file system provider.
> It does not communicate with the file system provider service yet.
> 
> Currently, for not supported operations SECURITY error is returned. For
> allowed, but not implemented operations, it is NOT_FOUND error.
> 
> Unit tests are quite trivial at this stage, but they will grow once more
> operations are implemented.
> 
> TEST=unit_test: FileSystemProviderAsyncFileUtilTest*
> BUG=248427
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=264462

TBR=kinaba@chromium.org,mtomasz@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=248427
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=264475

[dconnelly, 2014-04-17 12:11:31]

Created Revert of [fsp] Add an initial AsyncFileUtil.

[commit-bot: I haz the power, 2014-04-17 12:11:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dconnelly@chromium.org/240483008/1

[commit-bot: I haz the power, 2014-04-17 12:12:30]

Change committed as 264475