This ensures if we re-capture with different parameters that
we regenerate traces. It uses the sha1 so that it can be run
correctly from an open-source checkout.

Bug: angleproject:4590
Change-Id: I01a2eef037924c5acaaf124308315364e6f1d723
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2185157
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>