gpu: Add "main" file for Dawn perf tests target

Bug: dawn:208
Change-Id: I1cea34b19ac99f9bda6e916148075103cc7dcc60
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1764527
Reviewed-by: Kenneth Russell <[email protected]>
Commit-Queue: Austin Eng <[email protected]>
Cr-Commit-Position: refs/heads/master@{#689288}
1 file changed