Mandoline filesystem: Enable windows build.

Mandoline filesystem: Build the filesystem on windows.

This resolves name collisions with #defines in windows.h and does os specific path handling in a few places.

BUG=490237
Committed: https://crrev.com/3e8be89d1827aed47a9deeb7d1b6745258c17000
Cr-Commit-Position: refs/heads/master@{#332073}

[Elliot Glaysher, 2015-05-29 22:18:13]

erg@chromium.org changed reviewers:
+ sky@chromium.org

[sky, 2015-05-29 22:47:24]

LGTM

[Elliot Glaysher, 2015-05-29 22:51:21]

The CQ bit was checked by erg@chromium.org

[commit-bot: I haz the power, 2015-05-29 22:52:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1163713002/140001

[commit-bot: I haz the power, 2015-05-29 23:12:54]

Committed patchset #8 (id:140001)

[commit-bot: I haz the power, 2015-05-29 23:13:48]

Patchset 8 (id:??) landed as
https://crrev.com/3e8be89d1827aed47a9deeb7d1b6745258c17000
Cr-Commit-Position: refs/heads/master@{#332073}

[Elliot Glaysher, 2015-05-29 23:27:54]

A revert of this CL (patchset #8 id:140001) has been created in
https://codereview.chromium.org/1163523006/ by erg@chromium.org.

The reason for reverting is: Patch failed on Win 8 GN:

FAILED: ninja -t msvc -e environment.x64 -- E:\b\build\goma/gomacc.exe
"E:\b\depot_tools\win_toolchain\vs2013_files\VC\bin\amd64/cl.exe" /nologo
/showIncludes /FC
@obj/components/filesystem/filesystem_library.file_impl.obj.rsp /c
../../components/filesystem/file_impl.cc
/Foobj/components/filesystem/filesystem_library.file_impl.obj
/Fdobj/components/filesystem/filesystem_library_cc.pdb
e:\b\build\slave\win_x64_gn\build\src\components\filesystem\file_impl.cc(129) :
error C2220: warning treated as error - no 'object' file generated
e:\b\build\slave\win_x64_gn\build\src\components\filesystem\file_impl.cc(129) :
warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of
data
.