commit 414da244f00cf84ba4e02d3d855a73fc42fbe887
author Patrik Höglund <phoglund@webrtc.org> Mon Feb 24 12:16:03 2020
committer Commit Bot <commit-bot@chromium.org> Tue Feb 25 08:05:53 2020
tree e674978058139ebe64c730b67f2906414d11f73d
parent 82dcba489e36c06c719e4c442716742d49f496ae

Add PerfResultsReporter.

This is the WebRTC equivalent of testing/perf/perf_result_reporter.h
in Chromium. That class was introduced because the PrintResult
functions are quite hard to use right. It was easy to mix up
metrics, modifiers and stories, for instance.

I choose to introduce this new class because I need to create a new
API for PrintResult anyway. For instance, the important bool isn't
really supported by histograms. Also I would like to restrict units
to an enum because you cannot make up your own units anymore.
We could also have had a strictly checked string type, but that's
bad API design. An enum is better because the compiler will check
that the unit is valid rather than at runtime.

Furthermore, down the line we can probably make each reporter write
protos directly to /tmp and merge them later, instead of having a
singleton which writes results at the end and keeps all test results
in memory. This abstraction makes it easy to make a clean and simple
implementation of just that.

Steps:
1) land this
2) start rewriting perf tests to use this class
3) nuke PrintResult functions
4) don't convert units to string, convert directly from Unit
   to proto::Unit
5) write protos directly from this class (either through
   a singleton or directly) and nuke the perf results writer
   abstraction.

Bug: chromium:1029452
Change-Id: Ia919c371a69309130c797fdf01ae5bd64345ab2e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/168770
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30599}