And this also started failing on the Linux FYI bot at the same time.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/98859cdc638718d0399f36230c989d58b96de94a

commit 98859cdc638718d0399f36230c989d58b96de94a
Author: grunell <grunell@chromium.org>
Date: Mon Sep 19 10:28:27 2016

Disabling WebRtcApprtcBrowserTest.MANUAL_FirefoxApprtcInteropTest.

Test fails.

BUG= 648181 

TBR=phoglund@chromium.org
NOTRY=true

Review-Url: https://codereview.chromium.org/2352613002
Cr-Commit-Position: refs/heads/master@{#419426}

[modify] https://crrev.com/98859cdc638718d0399f36230c989d58b96de94a/chrome/browser/media/webrtc/webrtc_apprtc_browsertest.cc

Recent failures in  issue 640628  and  issue 626556 . Mozilla bug in https://bugzilla.mozilla.org/show_bug.cgi?id=1297729 (filed with  issue 640628 ).

Sorry for late follow-up. By looking at the runhooks step output from the last green build (#21889) and the first failing (#21890) we can see that for the green:
 INFO | Selected build: 2016-09-16-03-02-04-mozilla-central

and the first failure:
Downloaded firefox-nightly/2016-09-17-03-04-27-mozilla-central-firefox-51.0a1.en-US.linux-x86_64.tar.bz2

So it's the Firefox nightly build from Sept 17 that introduced the breakage, i.e. not a Chromium error (as we suspected).

jansson: do you think it would be a useful exercise for Jaspal to check if the interop is now working again?

Yeah sure.

No updates for 5 months -- is this a Pri-1?

Ouch, that means our only Firefox interop test has been disabled Since Sep 19, 2016 ([1] confirms this).

This is an unfortunate showcase of the bad things what can happen with ownerless bugs and disabled tests.
I guess the Blink>WebRTC component owners might have been missing this since it was in status ExternalDependency. I wonder if we need to address this in our triage process...

[1] https://cs.chromium.org/chromium/src/chrome/browser/media/webrtc/webrtc_apprtc_browsertest.cc?rcl=90659e8a6bbc7e40ea3145c19af3138f484beb52&l=276

I decided to take this on. The test passes on my local Linux workstation so we should be able to re-enable it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4762aebd36e6a5b18565bd9b76e419523e5ac903

commit 4762aebd36e6a5b18565bd9b76e419523e5ac903
Author: kjellander <kjellander@chromium.org>
Date: Thu Apr 06 17:00:27 2017

Re-enable Firefox interop test.

BUG= 648181 
TESTED=Passing local run on Linux with:
out/Release/browser_tests --gtest_filter=WebRtcApprtcBrowserTest.MANUAL_FirefoxApprtcInteropTest --run-manual --ui-test-action-max-timeout=350000 --test-launcher-jobs=1 --test-launcher-bot-mode --test-launcher-print-test-stdio=always

Review-Url: https://codereview.chromium.org/2805523003
Cr-Commit-Position: refs/heads/master@{#462516}

[modify] https://crrev.com/4762aebd36e6a5b18565bd9b76e419523e5ac903/chrome/browser/media/webrtc/webrtc_apprtc_browsertest.cc

Confirmed green builds:
https://build.chromium.org/p/chromium.webrtc/builders/Linux%20Tester/builds/28459
https://build.chromium.org/p/chromium.webrtc.fyi/builders/Linux%20Tester/builds/35768