Revert 264778 "[fsp] [recommit] Add an initial AsyncFileUtil."

Broke Linux ChromeOS ASan:

http://build.chromium.org/p/chromium.memory/buildstatus?builder=Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%283%29&number=938

> [fsp] [recommit] 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.
> 
> This patch has been previously committed and reverted due to test failures.
> See: https://codereview.chromium.org/236303017/
> 
> TEST=unit_test: FileSystemProviderAsyncFileUtilTest*
> BUG=248427
> 
> Review URL: https://codereview.chromium.org/242493002

TBR=mtomasz@chromium.org

Review URL: https://codereview.chromium.org/243153004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@264801 0039d316-1c4b-4281-b951-d872f2087c98
11 files changed