(This is a merge of http://go/wvgerrit/134404.)
There were two lines that were tripping Clang's `-Wshorten-64-to-32`
warning. This CL makes both conversions explicit to appease the warning.
There should be no change in behavior.
Bug: 194971260
Test: ODK Unit Tests
Change-Id: I6d111e9a4efc1f0e31b51e455c47c0e885d48e6b