Mark method as needed for testing.

There are tests for this method, but it is not actually used in the
application.

For now, I will mark it as needed for testing, so that ProGuard does not
remove it, but the long term solution is to clean up this bits of the
code.

Bug: 5594198
Change-Id: I67b5abdc0c9d3c729fb50d5981e3791508593148