commit c4e332b7622de011fbbea0fd5f3ec6161e5aad78
author Ahmed Nasr <anasr@google.com> Fri Apr 29 00:51:54 2022
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Apr 29 00:51:54 2022
tree 224b2a8dfe81217add2423ddd5ed820a8ef47642
parent 023529555939e01068874ddff3a2ea8455125efb

Change sampler collection parameter to optional #1.

Currently, when a sampler does not have data to report, it will
just drop the callback, this approach won't work if we collect
data from multiple samplers, for example using
AdditionalSamplersCollector, as the collector will not report any
data if only one sampler does not respond, so to avoid this we need
to change the callback to support optional MetricData, so it can be
run with absent data instead of dropping it.

In this first CL, a new method MaybeCollect that supports optional
MetricData is introduced, to avoid changing all samplers in the same
CL, MaybeCollect will be a wrapper of the old Collect method until
all samplers are migrated to use MaybeCollect directly.

Bug: b:209638899
Change-Id: I86e2bc3e159b5545d3002e92c6661f084004ab7b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3614872
Commit-Queue: Ahmed Nasr <anasr@google.com>
Reviewed-by: Tyler Garrett <tylergarrett@chromium.org>
Cr-Commit-Position: refs/heads/main@{#997499}