NaCl cleanup: Remove unneeded definition of ResolveFileToken()

NaCl cleanup: Remove unneeded definition of ResolveFileToken()

This will allow the ResolveFileToken field to be removed from
NaClValidationCache on the NaCl side.

Chromium no longer uses the NaCl side's ability to call back to
ResolveFileToken().  File tokens are handled entirely on the Chromium
side.

Removing this is safe because the NaCl side doesn't call
ResolveFileToken() if the NaClDesc doesn't have a file token
associated with it, or if ResolveFileToken is NULL (and we're setting
it to NULL using memset()).

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

Committed: https://crrev.com/747672ddb715596eade73524aa18a75aec236af0
Cr-Commit-Position: refs/heads/master@{#315050}

[Mark Seaborn, 2015-02-06 16:35:56]

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

[teravest, 2015-02-06 16:53:15]

lgtm

[Mark Seaborn, 2015-02-06 17:05:52]

The CQ bit was checked by mseaborn@chromium.org

[commit-bot: I haz the power, 2015-02-06 17:06:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/897353002/1

[commit-bot: I haz the power, 2015-02-06 17:09:09]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-06 17:09:51]

Patchset 1 (id:??) landed as
https://crrev.com/747672ddb715596eade73524aa18a75aec236af0
Cr-Commit-Position: refs/heads/master@{#315050}