GitLab

This adds a new target, profile_provider_unittest, as part of
chromiumos_preflight to make it build for cros_vm. The test will then be
added as part of the tests that run on cros_vm per build for the
chromium repo.

The test exercises the perf collector end-to-end, from the chrome browser
to debugd to make real perf collections. The test adds coverage to paths
that are mocked by current unit tests.

Bug: 1002751
Test: Reverse apply crrev.com/c/1764319 and check that the test crashes.
      Then apply crrev.com/c/1773881 and check that the test passes

Change-Id: I6d11a26dcd726f5bc4b8dabc9810e31f1370e5ec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1797948
Commit-Queue: Chinglin Yu <chinglinyu@chromium.org>
Reviewed-by: Gabriel Marin <gmx@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698853}