https://ci.chromium.org/buildbot/tryserver.chromium.win/win10_chromium_x64_rel_ng/55783

[ RUN      ] DataReductionProxyProtocolEmbeddedServerTest.EmbeddedTestServerBypassRetryOnPostConnectionErrors
Received fatal exception EXCEPTION_ACCESS_VIOLATION
Backtrace:
	net::NetLog::ThreadSafeObserver::OnAddEntryData [0x00007FF6D78D6ABE+30]
	net::NetLog::AddEntry [0x00007FF6D78D6C4C+156]
	net::NetLogWithSource::AddEntry [0x00007FF6D78EB4C3+51]
	net::nqe::internal::EventCreator::MaybeAddNetworkQualityChangedEventToNetLog [0x00007FF6D7AE6BE0+432]
	net::NetworkQualityEstimator::ComputeEffectiveConnectionType [0x00007FF6D7A0B2D1+913]
	net::NetworkQualityEstimator::MaybeComputeEffectiveConnectionType [0x00007FF6D7A0BBA1+465]
	net::NetworkQualityEstimator::AddAndNotifyObserversOfThroughput [0x00007FF6D7A0AB41+753]
	net::NetworkQualityEstimator::OnNewThroughputObservationAvailable [0x00007FF6D7A09EAD+189]
	base::internal::FunctorTraits<base::RepeatingCallback<void __cdecl(int)>,void>::Invoke<base::RepeatingCallback<void __cdecl(int)> const & __ptr64,int const & __ptr64> [0x00007FF6D8CC1073+115]
	base::debug::TaskAnnotator::RunTask [0x00007FF6D786C863+291]
	base::internal::IncomingTaskQueue::RunTask [0x00007FF6D787361E+126]
	base::MessageLoop::RunTask [0x00007FF6D77C5B29+665]
	base::MessageLoop::DeferOrRunPendingTask [0x00007FF6D77C5F7F+191]
	base::MessageLoop::DoWork [0x00007FF6D77C61FD+573]
	base::MessagePumpForIO::DoRunLoop [0x00007FF6D7877308+24]
	base::MessagePumpWin::Run [0x00007FF6D7876448+104]
	base::MessageLoop::Run [0x00007FF6D77C537C+204]
	base::RunLoop::Run [0x00007FF6D77C769C+252]
	net::test_server::EmbeddedTestServer::PostTaskToIOThreadAndWait [0x00007FF6D7E18318+280]
	net::test_server::EmbeddedTestServer::ShutdownAndWaitUntilComplete [0x00007FF6D7E17360+192]
	net::test_server::EmbeddedTestServer::~EmbeddedTestServer [0x00007FF6D7E1713A+122]
	net::TestNetworkQualityEstimator::~TestNetworkQualityEstimator [0x00007FF6D7E16A9B+75]
	net::TestNetworkQualityEstimator::`scalar deleting destructor' [0x00007FF6D7E16830+16]
	data_reduction_proxy::DataReductionProxyTestContext::~DataReductionProxyTestContext [0x00007FF6DA064E95+117]
	data_reduction_proxy::DataReductionProxyTestContext::`scalar deleting destructor' [0x00007FF6DA0614D0+16]
	data_reduction_proxy::DataReductionProxyProtocolEmbeddedServerTest::~DataReductionProxyProtocolEmbeddedServerTest [0x00007FF6D5BE656A+106]
	data_reduction_proxy::DataReductionProxyProtocolEmbeddedServerTest_EmbeddedTestServerBypassRetryOnPostConnectionErrors_Test::`scalar deleting destructor' [0x00007FF6D5BE6340+16]
	testing::TestInfo::Run [0x00007FF6D6008685+325]
	testing::TestCase::Run [0x00007FF6D60089FA+250]
	testing::internal::UnitTestImpl::RunAllTests [0x00007FF6D600D39F+671]
	testing::UnitTest::Run [0x00007FF6D600D025+165]
	base::TestSuite::Run [0x00007FF6D7E332D6+118]
	base::LaunchUnitTests [0x00007FF6D7E2F282+178]
	main [0x00007FF6D5A03835+81]
	__scrt_common_main_seh [0x00007FF6DA916AC9+285] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283)
	BaseThreadInitThunk [0x00007FFD38C78364+20]
	RtlUserThreadStart [0x00007FFD3B5D5E91+33]


Marking P1. It looks like there has been a recent code change causing this crash.