perfetto: add trace stats to json trace

To help us debug.

Bug: 919187
Change-Id: I9d0ac32d046aef3895025dde559fdc7dadf3e136
Reviewed-on: https://chromium-review.googlesource.com/c/1455898
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Commit-Queue: Eric Seckler <eseckler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629566}
1 file changed