Replace libchrome string_util to libbase strings

As part of the effort to uprev libchrome in Android, we are
removing Android dependencies to libchrome utility functions
that are not strictly required.

This CL remove the usage of base/string/string_util.h and replace
by android-base/string.h

Change-Id: I8a5b12d0dce746886f1d0dd8c26e51f323aaf5da
Test: m
Bug: 360917504
1 file changed