Use |probe_cluster_id| to cluster packets.

Introduced new class DelayBasedProbingEstimator which is a copy of
RemoteBitrateEstimatorAbsSendTime with only minor changes. This makes probing
more reliable but is still not usable for mid-call probing.

BUG=

Review-Url: https://codereview.webrtc.org/2038023002
Cr-Original-Commit-Position: refs/heads/master@{#13195}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 863a8264cc0d8499fb7b666cb8be868ab95b1bff
7 files changed