Make a NaClDesc ctor for creating descs from NaClFileInfo.

src/trusted/desc_cacheability/desc_cacheability.h

Index: src/trusted/desc_cacheability/desc_cacheability.h
diff --git a/src/trusted/desc_cacheability/desc_cacheability.h b/src/trusted/desc_cacheability/desc_cacheability.h
index 38e0ee6e344c452e1cc5ee0d99ebbbc2886b788e..a94a8d9daaf7d6cc0fa429ef3f24a1bb3031f623 100644
--- a/src/trusted/desc_cacheability/desc_cacheability.h
+++ b/src/trusted/desc_cacheability/desc_cacheability.h
@@ -16,24 +16,6 @@ struct NaClFileToken;
 struct NaClValidationCache;
 
 /*
- * NaClDescSetFileToken associates the contents of |token| with |desc|
- * as NaClDesc metadata.  Any other metadata previously associated
- * with |desc| is released / destroyed.  Returns non-zero value for
- * success.  (Boolean function.)
- */
-int NaClDescSetFileToken(struct NaClDesc *desc,
-                         struct NaClFileToken const *token);
-
-/*
- * NaClDescGetFileToken checks if there is metadata associated with
- * |desc| that contains a previously serialized NaClFileToken object.
- * If so, it writes the NaClFileToken pointed to by |out_token| with
- * the file token, and returns a non-zero value.  (Boolean function.)
- */
-int NaClDescGetFileToken(struct NaClDesc *desc,
-                         struct NaClFileToken *out_token);
-
-/*
  * NaClExchangeFileTokenForMappableDesc checks the |file_token| with
  * the |validation_cache| and, if the file token is valid, i.e., for a
  * file that should be safe to map (immutable for the duration of our