Convert libchrome scripts to python 3 am: 22b8126fb5 am: 2f8caa9aa8

Original change: https://android-review.googlesource.com/c/platform/external/libchrome/+/2210336

Change-Id: I65e8dd5abb941290e8fc7110bd5ec7b791bc5f77
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>