commit b619936dee2807ca99ae2ed76956997bd2b43d6f
author Henrik Boström <hbos@webrtc.org> Mon Mar 12 09:27:55 2018
committer Commit Bot <commit-bot@chromium.org> Mon Mar 12 10:54:09 2018
tree eb4d6697aa64eacc727552bd116dee8a6b137d08
parent 0f1c0bd3265d337eba32faacad9cc4e36bb1f53e

Stats traversal algorithm added.

This is part of the work to add a selector argument to getStats().

Changes:
- TakeReferencedStats() added, which traverses the stats graph and takes
  any stats from the report that are directly or indirectly accessible
  from the starting stats objects in the stats graph. The result is
  returned as a stats report.
- GetStatsReferencedIds(), an efficient helper function for getting
  neighbor stats object IDs.
- RTCStatsReport::Take(), removed the stats object with the given ID and
  returns ownership of it (so that it can be added to another report).

TakeReferencedStats() is tested with a bunch of sample stats graphs.

GetStatsReferencedIds() is tested in the rtcstats_integrationttest.cc,
making sure the expected IDs are returned. The expected IDs are the
values of the stats object members with the "Id" or "Ids" suffix.

Design doc:
https://docs.google.com/document/d/18BywbtXgHCjsbR5nWBedpzqDjAfXrFSTJNiADnzoK0w/edit?usp=sharing

Bug: chromium:680172
Change-Id: I5da9da8250da0cb05adb864015901393a4290776
Reviewed-on: https://webrtc-review.googlesource.com/60869
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22381}