Update ClipDescription.getTimeStamp to use currentTimeMillis timebase.

Bug: 37419581
Test: cts-tradefed run singleCommand cts-dev -m CtsContentTestCases -t \
      android.content.cts.ClipDescriptionTest

Change-Id: I699bfc073c471534eee0b3aa0300a6b6682ab8dd
2 files changed