Promote chrome_sizes on chromium.chrome bots out of experimental.

Got green runs on the three desktop bots:
https://ci.chromium.org/p/chrome/builders/ci/linux-google-rel/5659
https://ci.chromium.org/p/chrome/builders/ci/win-google-rel/5994
https://ci.chromium.org/p/chrome/builders/ci/mac-google-rel/2935

And trybot mirrors are not polluting the perf dashboard's streams for the
CI bots since they upload to a different namespace based on master:
https://codesearch.chromium.org/chromium/src/tools/perf/core/perf_dashboard_machine_group_mapping.json

Bug: 961548
Change-Id: I9aae3c16eda8b2758e47a80f31a717c8c69f8772
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1656017
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672102}
2 files changed