Merge "Add String16#contains and strstr16 methods." into nyc-dev
am: 8b452b876b

* commit '8b452b876b90dcfff1dab9012b65b5e67c4531a4':
  Add String16#contains and strstr16 methods.

Change-Id: I4174527fa81cc725eb874c664c66b75319534d8f