Add a new calmbench tool for noiseless nanobench

This tool can quickly check all nanobench tests including svgs
and skps (<5 minutes for CPU, ~30 minutes for GPU) and find
significant performance regressions without much noise.

This tool is not only faster (lower latency to get regression
alerts), but also more sensitive compared to our k-means and
step-fitting bots (especially for changes that only affect very
few benches). It may still miss some regressions, but the
regressions reported should be valid with very high probability.

Bug: skia:
Change-Id: I02115e6c5ab630e4c56b2087ffeb5cae1d4a618e
Reviewed-on: https://skia-review.googlesource.com/50060
Commit-Queue: Yuqian Li <liyuqian@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
2 files changed