resolve merge conflicts of 1726942 to nyc-dev-plus-aosp am: ca4b041
am: cf71a21

* commit 'cf71a21b88e74e04c38cfd83cb549f2a66bb7ba0':
  Preserve generalized reduction combiner function for use by driver.

Change-Id: I6b28bd686bf55bf10ed3c7f577a9330e7befdfa9