Merge "SupportLeanbackshowcase: clean up preference fragment code" into nyc-dev am: 097514b34c
am: 0ba81b53e9

* commit '0ba81b53e910e3e5c9f9ed86ae41870baf426ebc':
  SupportLeanbackshowcase: clean up preference fragment code

Change-Id: I5edc1876f5ad17f06b76da0ce1450f73592202f5