GitLab

These metrics are high level and do not include subscopes.

Examples:
- v8-gc-mark-compactor-total
- v8-gc-mark-compactor-mmu
- v8-gc-mark-compactor-marking-total

No-try: true
Tbr: nednguyen@chromium.org
Change-Id: I6feafb6971f0904d1d9bd31201d1be2e63258049
Reviewed-on: https://chromium-review.googlesource.com/c/1304479Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603479}