Austin Eng cfc9c6e322 Make perf test tracing thread-safe
The Metal driver calls command buffer completion callbacks on a
separate thread so enqueueing these trace events needs to be made
thread-safe. In the future, Dawn will probably have other threads
that also require thread-safe tracing.

In this CL, each thread records trace events into its own buffer,
and all buffers concatenated when trace events are acquired.

Bug: dawn:254, dawn:208
Change-Id: I0f1abd404568d838091066a8f27a3bf98fa764b9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/13080
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
2019-11-11 23:15:56 +00:00
..
2019-11-11 18:39:08 +00:00
2019-11-11 23:15:56 +00:00
2019-11-07 22:23:29 +00:00