Merge "Preserve generalized reduction combiner function for use by driver." into nyc-dev am: 791d57c
am: 70bf334

* commit '70bf33455584bdbe43ef089b7e54f7b9a795fe77':
  Preserve generalized reduction combiner function for use by driver.

Change-Id: I8f1d9d8fbdea0be31553341c90df3da88fc95d32