Merge "Fill in javadocs for translation feature." into sc-dev am: 1553fc7f am: 4b02f452 am: e6664abb

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15597859

Change-Id: I30473108e8aa95b6a71e80fe525a981d4f46aee4