[presubmit] Base64 encode for config validation
[presubmit] Base64 encode for config validation

Bug: 782328
Change-Id: I5219416371cc1b3dfc1f93fee6d1067ef5a6e3d3
Reviewed-on: https://chromium-review.googlesource.com/758719
Commit-Queue: Mun Yong Jang <cafb0219fa074fe0c089777a22a0dd4cc2126d7e@google.com>
Reviewed-by: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools