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 am: 6598f780
am: 7423e937

* commit '7423e937':
  For reference extension builds, update book_path to reference the appropriate file location.

Change-Id: I2c0a3176f2346e61ce1f0fa79238def5134ec7db