Replace chrome string util with android base ones am: b9a9aa22ba am: 6f7126ea3b

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3309177

Change-Id: I0deba2e8d964cae8d80f7017a9bda98d4febd02e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>