This is a reland of 028367fe

Should work on Skia after https://skia-review.googlesource.com/c/skia/+/244116

Original change's description:
> depot_tools: Use vpython to execute fetch.
>
> Bug: 1002153
> Change-Id: I11286bebc23bedada239d6ddb8ebb86207a41485
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1815707
> Reviewed-by: Anthony Polito <apolito@google.com>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
> Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>

Bug: 1002153
Change-Id: Ifdde3c4a817ab6ca222c82c5448d630e85bf2a4b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1827719Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>