[Sampling profiler] Add SampleScenario test utility function

Encapsulates unwind scenario sampling into a dedicated function
and reuses within the test code.

Bug: 909957
Change-Id: Ia73e3853b050c284066d9c3bbb318bd0653f8530
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582026
Reviewed-by: Charlie Andrews <charliea@chromium.org>
Commit-Queue: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653680}
1 file changed