For reference extension builds, update book_path to reference the appropriate...

For reference extension builds, update book_path to reference the appropriate file location. am: 8dbd7b96 am: ce46b862
am: 1d2dbfe4

* commit '1d2dbfe4':
  For reference extension builds, update book_path to reference the appropriate file location.

Change-Id: Id5ddec169d92b36f05a1d29b189b92f74396acb5