Merge "Fill in javadocs for translation feature." into sc-dev am: 1553fc7f am: 4b02f452 am: db0fbc2f

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

Change-Id: I2c41ed4318346f9a0a5abcd8aabdd1d1c787425d