Remove redudant string conversions

In the review of ag/26174212, an unnecessary string conversion was
identified; this CL corrects that, plus two other instances in
the same function.

Bug: 314732730
Test: Presubmit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:60e4fdfa0897b94c003ba3df3b39a16e10c886d1

)
Merged-In: Id2b620088e12266f041be864271493ffe7e1a3b1
Change-Id: Id2b620088e12266f041be864271493ffe7e1a3b1
Signed-off-by: Edward Liaw <edliaw@google.com>