https://build.chromium.org/p/chromium.perf/builders/Win%20Builder/builds/86175 is the relevant build. https://build.chromium.org/p/chromium.perf/builders/Win%20Builder/builds/86175/steps/steps/logs/stdio shows the logdog messages. There's a bunch of this at the end:

[W2017-06-21T11:10:48.292992-07:00 3676 0 pubsubOutput.go:220] TRANSIENT error publishing messages; retrying... {"error":"rpc error: code = 13 desc = connection error: desc = \"transport: read tcp 192.168.110.237:56219->172.217.12.106:443: wsarecv: An existing connection was forcibly closed by the remote host.\"", "count":1, "delay":"500ms", "pubsub":"pubsub(projects/luci-logdog/topics/logs)"}


Not sure if logdog could do anything about this, but it seems bad that logdog has been stuck here for about an hour.