tracing: Initialize track events conditionally

If V8 is running in a context where Perfetto hasn't been initialized
(e.g., as part of mksnapshot), don't try to initialize track events
either.

Since perfetto::Tracing::IsInitialized() was only added recently, we
also roll Perfetto to the latest revision. This also requires updating
the proto_library GN template together with the underlying libprotobuf
dependency.

Bug: chromium:1006541
Change-Id: Icec626b7ed78264a81f1a80d73d60be3bde0d908
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2632590


Commit-Queue: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Auto-Submit: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72130}