Merge "Renamed getTimeStamp to getTimestampMillis and added docs." am: 6f1b7122f3 am: d8935b34f4 am: 50ccf0437f am: 063a4aa8dd am: 0c0911fad0

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1869978

Change-Id: I0148ca062998af9eb87545b562966b510b8de8b9