Fix sandbox ASan test to cope with forward slashes in __FILE__

Fix sandbox ASan test to cope with forward slashes in __FILE__

gn invokes the compiler with forward slash paths while gyp does not.
This test failed when I ported WinASan to gn.

This CL doesn't use base::FilePath::BaseName because then I'd need to
get a wide string __FILE__, which is tricky.

R=wfh@chromium.org
BUG=598761
Committed: https://crrev.com/3dbbe337ce92c737b5c5c497c5ceb7fd4c81f85f
Cr-Commit-Position: refs/heads/master@{#383990}

[Will Harris, 2016-03-30 03:22:28]

lgtm

[Reid Kleckner, 2016-03-30 15:39:00]

The CQ bit was checked by rnk@chromium.org

[commit-bot: I haz the power, 2016-03-30 15:39:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1837403002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1837403002/1

[commit-bot: I haz the power, 2016-03-30 16:08:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-30 16:10:06]

Description was changed from

==========
Fix sandbox ASan test to cope with forward slashes in __FILE__

gn invokes the compiler with forward slash paths while gyp does not.
This test failed when I ported WinASan to gn.

This CL doesn't use base::FilePath::BaseName because then I'd need to
get a wide string __FILE__, which is tricky.

R=wfh@chromium.org
BUG=598761
==========

to

==========
Fix sandbox ASan test to cope with forward slashes in __FILE__

gn invokes the compiler with forward slash paths while gyp does not.
This test failed when I ported WinASan to gn.

This CL doesn't use base::FilePath::BaseName because then I'd need to
get a wide string __FILE__, which is tricky.

R=wfh@chromium.org
BUG=598761

Committed: https://crrev.com/3dbbe337ce92c737b5c5c497c5ceb7fd4c81f85f
Cr-Commit-Position: refs/heads/master@{#383990}
==========

[commit-bot: I haz the power, 2016-03-30 16:10:07]

Patchset 1 (id:??) landed as
https://crrev.com/3dbbe337ce92c737b5c5c497c5ceb7fd4c81f85f
Cr-Commit-Position: refs/heads/master@{#383990}