GitLab

Records timestamps along with samples and plumbs them through to
the ProfileBuilder interface. The CallStackProfileBuilder subclass
will be updated in a following CL to record the timestamps, to
support retrospective tagging of metadata on the samples.

Bug: 1034758
Change-Id: Ic631d47773db5ce8ed5117c08aba5d5931cb7884
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1972931Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: oysteine <oysteine@chromium.org>
Commit-Queue: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726526}