All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=599577

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg8O_PtgoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgiLrDqgoM


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

chromium-webrtc-rel-mac

CL range:
http://test-results.appspot.com/revision_range?start=383461&end=383999

There is some overlap with the CL range mentioned in bug 599569, but I've filed a separate bugs for these graphs in case there are two distinct causes. One big difference related to the CL ranges is that this bug's range includes a WebRTC roll (https://codereview.chromium.org/1839343002). Changes in that roll:
https://chromium.googlesource.com/external/webrtc/trunk/webrtc.git/+log/ce55976..80eacc6

Nothing obvious stands out, though. hbos@, can you take a look?

I think I know what this is, that machine was upgraded from 10.9 to 10.10 at March 30, which fits with the regression. I'll leave it to hbos@ to close the bug though (in case there may be something else).

What about chromium-webrtc-rel-win10 and chromium-webrtc-trunk-tot-rel-mac of which the other two regression bugs concern?
(https://bugs.chromium.org/p/chromium/issues/detail?id=599569 and https://bugs.chromium.org/p/chromium/issues/detail?id=599580)

My comment #4 only touches the Mac machines of chromium.webrtc[.fyi]. 
I posted a similar comment in  bug 599580  now (sorry I thought I did that last week but apparently I missed that one).

The Windows one is likely a true regression, I'm most certain the Mac ones are caused by the machine environmental changes.

Closing due to numbers explainable by upgrade.