All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=762556

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=14892b03a3b78ff516c3e7d1a4a121dc4eeb4d23e046139631f1932fac0a494e


Bot(s) for this bug's original alert(s):

webrtc-android-tests-nexus5

Could this be related to your change?

https://chromium.googlesource.com/external/webrtc/+log/a0a5b98937de0f0bf90e17011d2cbc8c632cb409..f33cee7534f0469330b6b7aa57f84eec4b082598

Added some more Ulpfec alerts to the report.

I've done some testing and concluded that these regressions are not caused by the nack change linked. 
Instead, I can repro them locally by rolling past

commit d4fac6957e14068f8dbf2ab4a20006b1df044274
Author: philipel <philipel@webrtc.org>
Date:   Mon Sep 4 07:03:46 2017 -0700

    Unwrap picture ids in the RtpFrameReferencerFinder.


Is the even a negative btw? Isn't being able to achieve a more stable high media and fec bitrate a good thing?

In any case, philipel@ ptal

Possible that it's not negative, but I'd like to understand why. :)

Maybe it makes sense then that we only see Ulpfec alerts, but no Flexfec alerts: Ulpfec packets share the sequence number space with the media packets, but Flexfec does not.

Yes, that sounds like a reasonable explanation. Sounds like we might have a bug here.

Any progress on this one?

The following revision refers to this bug:
  https://webrtc.googlesource.com/src.git/+/1610f94ee35f788de9317a7c434448930eb121ed

commit 1610f94ee35f788de9317a7c434448930eb121ed
Author: philipel <philipel@webrtc.org>
Date: Thu Dec 14 14:22:13 2017

Don't cast picture ids (of type int64_t) to int.

Also cleaned up a bit in RtpFrameReferenceFinder.

Bug:  chromium:762556 
Change-Id: Ib08d2e7ce4b146b359ce9ba823f3aa15776c71bc
Reviewed-on: https://webrtc-review.googlesource.com/32301
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21282}
[modify] https://crrev.com/1610f94ee35f788de9317a7c434448930eb121ed/modules/video_coding/frame_buffer2.cc
[modify] https://crrev.com/1610f94ee35f788de9317a7c434448930eb121ed/modules/video_coding/frame_buffer2.h
[modify] https://crrev.com/1610f94ee35f788de9317a7c434448930eb121ed/modules/video_coding/rtp_frame_reference_finder.cc
[modify] https://crrev.com/1610f94ee35f788de9317a7c434448930eb121ed/modules/video_coding/rtp_frame_reference_finder.h
[modify] https://crrev.com/1610f94ee35f788de9317a7c434448930eb121ed/video/video_receive_stream.cc