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

* commit '5500bb1d6d5d5c49f7bb5d81b48a707f1ade75ab':
  API review feedback for ProgressBar

Change-Id: If6e1d8d9211b86030d8a678b6030df4cc50c9e77