NaCl cleanup: Remove references to native_client/src/public/nacl_file_info.h

NaCl cleanup: Remove references to native_client/src/public/nacl_file_info.h

It's no longer necessary for the NaCl side to define and refer to the
NaClFileToken struct.

So we can change the Chromium side to define NaClFileToken, instead of
using the definition from nacl_file_info.h.  This will let us remove
nacl_file_info.h from the NaCl side.

We copy the comment from nacl_file_info.h.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=4073
TEST=build

Committed: https://crrev.com/3faf5be059e1a62895f4ef665f2dc5e628bde4b8
Cr-Commit-Position: refs/heads/master@{#315317}

[Mark Seaborn, 2015-02-08 19:43:16]

mseaborn@chromium.org changed reviewers:
+ teravest@chromium.org

[teravest, 2015-02-09 15:17:19]

lgtm

[Mark Seaborn, 2015-02-09 16:07:04]

The CQ bit was checked by mseaborn@chromium.org

[commit-bot: I haz the power, 2015-02-09 16:08:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/903333002/20001

[commit-bot: I haz the power, 2015-02-09 16:13:34]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-09 16:14:30]

Patchset 2 (id:??) landed as
https://crrev.com/3faf5be059e1a62895f4ef665f2dc5e628bde4b8
Cr-Commit-Position: refs/heads/master@{#315317}