With warmup and/or longer runs, the benchmark results are more reliable.
This CL also splits the benchmark into smaller ones for easier management.

Change-Id: Ieba0734bef841d131b3184938109ca179994e173
Reviewed-on: https://chromium-review.googlesource.com/1188572Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Hai Dang <dhai@google.com>
Cr-Commit-Position: refs/heads/master@{#55422}