Merge "API review feedback for ProgressBar" into nyc-dev am: 5500bb1d6d am: c1a3af4546
am: 06f931e8ea

* commit '06f931e8eae92cbfb24983502d9cdf41f1284dad':
  API review feedback for ProgressBar

Change-Id: I8a38db908a3b01b33787d4f9e2c6483b3c325ef6