This is for python3 compatibility.

Bug: b/177465438
Change-Id: I4770136ea702bcaf7a8b644ef842db2f1a7d1200
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2717272Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Chris Hall <chrishall@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>