mDNS hostname obfuscation has been landed preffed off for around two weeks. I've been running it preffed on locally without problems. It is time to try it on Nightly.

I ran one last try job just to be safe [1] and it appears we have a consistent failure on win32 opt with one of the DataChannel web platform tests. I'll need to investigate that before this can be landed.

[1] https://treeherder.mozilla.org/#/jobs?repo=try&selectedJob=272644563&revision=053676fe7eab3f03a0775b22433a05cdee571432

Unfortunately, this pretty clearly introduces a new intermittent: https://treeherder.mozilla.org/#/jobs?repo=try&revision=8867487ba0035d454f5f84c866f486aab8bff214

I spent a good chunk of time investigating this as if it were a shutdown crash that was undetected by the test framework, but it appears that this is actually just a timing problem. If I increase the timeout in get_test_window, I get a green run [1]. Hopefully there is a way of doing this in the test metadata.

[1] https://treeherder.mozilla.org/#/jobs?repo=try&revision=8bd0a13490e2c13d43f41f685cca9594c70603ca

Running this test leads to intermittent "unable to find test window"
failures on 32 bit windows. If the timeout to get_test_window() in
executormarionette.py is increased, the failure goes away, but there
is no way in the framework to increase this timeout for a single
test.

Depends on D49956

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&fromchange=0dfb81870b77e26e03415627ca6407daec0ea1f0&tochange=a465ca5c85f272e8db9088cad2d9217adabcb6e3&searchStr=mochitests%2Cwithout%2Ce10s%2C&selectedJob=274651202

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=274647259&repo=autoland&lineNumber=90480
https://treeherder.mozilla.org/logviewer.html#?job_id=274647259&repo=autoland

Backout link: https://hg.mozilla.org/integration/autoland/rev/a465ca5c85f272e8db9088cad2d9217adabcb6e3

[task 2019-11-05T16:32:09.802Z] 16:32:09 INFO - TEST-INFO | started process screencapture
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - TEST-INFO | screencapture: exit 0
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - TEST-UNEXPECTED-FAIL | dom/presentation/tests/mochitest/test_presentation_datachannel_sessiontransport.html | client's builder reports error 2152398862
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - SimpleTest.ok@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:277:18
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - onError@chrome://mochitests/content/chrome/dom/presentation/tests/mochitest/test_presentation_datachannel_sessiontransport.html:100:7
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - _cleanup@resource://gre/modules/PresentationDataChannelSessionTransport.jsm:181:22
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - notify@resource://gre/modules/PresentationDataChannelSessionTransport.jsm:142:12
[task 2019-11-05T16:32:09.926Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Connection 0x135279000/Channel 0x120a73af0: Closing stream 1
[task 2019-11-05T16:32:09.927Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Connection 0x135279000: Resetting outgoing stream 1
[task 2019-11-05T16:32:09.927Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Connection 0x135279000: Sending outgoing stream reset for 1 streams
[task 2019-11-05T16:32:09.927Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: E/DataChannel ***failed: setsockopt RESET, errno 2
[task 2019-11-05T16:32:09.927Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel DataChannelConnection labeled presentationAPI(0x120a73af0) (stream 1) changing ready state CONNECTING -> CLOSING
[task 2019-11-05T16:32:09.933Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: I/signaling [main|PeerConnectionImpl] PeerConnectionImpl.cpp:2229: CloseInt: Closing PeerConnectionImpl 6188e45c1a1bb0a1; ending call
[task 2019-11-05T16:32:09.934Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: I/jsep [1572971499751927 (id=33 url=chrome://mochitests/content/chrome/dom/presentation/tests/mochitest/test_presentation_datachannel_s]: stable -> closed
[task 2019-11-05T16:32:09.934Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: I/signaling [main|PeerConnectionImpl] PeerConnectionImpl.cpp:2235: CloseInt: Destroying DataChannelConnection 0x135279000 for 6188e45c1a1bb0a1
[task 2019-11-05T16:32:09.934Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Destroying DataChannelConnection 0x135279000
[task 2019-11-05T16:32:09.934Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Closing all channels (connection 0x135279000)
[task 2019-11-05T16:32:09.935Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel DataChannelConnection labeled transport_0 (0x135279000) switching connection state CONNECTING -> CLOSED
[task 2019-11-05T16:32:09.935Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Connection 0x135279000/Channel 0x120a73af0: Closing stream 1
[task 2019-11-05T16:32:09.935Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Removing channel 1 : 0x120a73af0
[task 2019-11-05T16:32:09.935Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Channel already closing/closed (2)
[task 2019-11-05T16:32:09.935Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel closing pending channel 0x120a73af0, stream 1
[task 2019-11-05T16:32:09.935Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Connection 0x135279000/Channel 0x120a73af0: Closing stream 1
[task 2019-11-05T16:32:09.936Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Removing channel 1 : 0x120a73af0
[task 2019-11-05T16:32:09.936Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Channel already closing/closed (2)
[task 2019-11-05T16:32:09.936Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Connection 0x135279000: Sending outgoing stream reset for 1 streams
[task 2019-11-05T16:32:09.936Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: E/DataChannel ***failed: setsockopt RESET, errno 2
[task 2019-11-05T16:32:09.936Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Main Thread]: D/DataChannel Clearing resets for 1 streams
[task 2019-11-05T16:32:09.937Z] 16:32:09 INFO - GECKO(2109) | [(null) 2109: Socket Thread]: D/DataChannel Deregistered 0x135279000 from the SCTP stack.
[task 2019-11-05T16:32:09.937Z] 16:32:09 INFO - Not taking screenshot here: see the one that was previously logged

We need to disable mDNS hostnames when we're not in the content process: https://treeherder.mozilla.org/#/jobs?repo=try&revision=4a93d35bcb72f234aa0030292d835308a72dd941. I'll start another try job that hits a few other configurations, but I think this should do it.

Larger try job: https://treeherder.mozilla.org/#/jobs?repo=try&revision=9a52d191ac9289f7f1de47ade9d85dd324196955

The mDNS code makes use of the StunAddrsRequest which only exists when
running in the content process, so we need to disable mDNS when we are not
running in the content process.

Depends on D51618

https://hg.mozilla.org/mozilla-central/rev/eeb7467c300f
https://hg.mozilla.org/mozilla-central/rev/6a7b78f2d462
https://hg.mozilla.org/mozilla-central/rev/e053b59af7f4