My guess would be that the new ResumeMainJobLaterCanceled test added in https://chromium-review.googlesource.com/c/chromium/src/+/805354 is leaving some global state set that is "leaking" into the DelayedTCPWithLargeSrtt test, causing it to crash.

Sorry about the breakage. 
Is there a way that I can reproduce this locally?

Re #2: We see this fail under Fuchsia, but for some reason only on our bots; I tried to repro locally but wasn't able to reproduce the failure, sorry. :(

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fa52ad99a73551c549ab48867a649c1276e893a2

commit fa52ad99a73551c549ab48867a649c1276e893a2
Author: Helen Li <xunjieli@chromium.org>
Date: Tue Dec 05 03:21:25 2017

Reset global scoped task environment in http_stream_factory_impl_job_controller_unittest.cc

Reset the NetTestSuite's global task environment in unit test so the MOCK_TIME
environment doesn't leak into subsequent tests.

Bug:  791804 
Change-Id: Ic5df1fc6c21c7ef6b88bff2d05a68b4636b7650a
Reviewed-on: https://chromium-review.googlesource.com/807287
Commit-Queue: Helen Li <xunjieli@chromium.org>
Reviewed-by: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521603}
[modify] https://crrev.com/fa52ad99a73551c549ab48867a649c1276e893a2/net/http/http_stream_factory_impl_job_controller_unittest.cc

The bot seems happy now :)