See

https://build.chromium.org/p/chromium.webrtc/builders/Win7%20Tester/builds/27822/steps/browser_tests/logs/stdio

for details.

[3184:1824:0713/143206:FATAL:rtc_peer_connection_handler.cc(443)] Check failed: main_thread_->BelongsToCurrentThread(). 
Backtrace:
	base::debug::StackTrace::StackTrace [0x0255BFD7+23]
	logging::LogMessage::~LogMessage [0x025187A1+49]
	content::RTCPeerConnectionHandler::~RTCPeerConnectionHandler [0x023E83C9+641]
	rtc::RefCountedObject<content::`anonymous namespace'::SetSessionDescriptionRequest>::`vector deleting destructor' [0x023E8604+17]
	rtc::RefCountedObject<content::`anonymous namespace'::CreateSessionDescriptionRequest>::Release [0x023EB9C1+23]
	webrtc::PeerConnection::OnMessage [0x01673D48+154]
	jingle_glue::JingleThreadWrapper::Dispatch [0x034EFC50+131]
	jingle_glue::JingleThreadWrapper::RunTask [0x034F0326+244]
	base::internal::InvokeHelper<1,void>::MakeItSo<void (__thiscall media::AudioRendererImpl::*const &)(enum media::BufferingState),base::WeakPtr<media::AudioRendererImpl>,enum media::BufferingState const &> [0x02425BEF+43]
	base::internal::Invoker<base::internal::BindState<void (__thiscall media::AudioRendererImpl::*)(enum media::BufferingState),base::WeakPtr<media::AudioRendererImpl>,enum media::BufferingState>,void __cdecl(void)>::RunImpl<void (__thiscall media::AudioRende [0x02425C20+38]
	base::internal::Invoker<base::internal::BindState<void (__thiscall media::AudioRendererImpl::*)(enum media::BufferingState),base::WeakPtr<media::AudioRendererImpl>,enum media::BufferingState>,void __cdecl(void)>::Run [0x024266D1+22]
	base::debug::TaskAnnotator::RunTask [0x0258F327+247]
	base::MessageLoop::RunTask [0x025274BB+1211]
	base::MessageLoop::DoWork [0x025266CE+606]
	base::MessagePumpDefault::Run [0x02568348+424]
	base::MessageLoop::RunHandler [0x02526FF7+103]
	base::RunLoop::Run [0x025299E9+41]
	base::Thread::Run [0x02549195+21]
	base::Thread::ThreadMain [0x02549876+454]
	base::PlatformThread::Sleep [0x02533D52+290]
	BaseThreadInitThunk [0x772C7C04+36]
	RtlInitializeExceptionChain [0x775DAB8F+143]
	RtlInitializeExceptionChain [0x775DAB5A+90]

Backtrace:
	base::debug::BreakDebugger [0x0255D499+9]
	logging::InitChromeLogging [0x036BB282+759]
	logging::LogMessage::~LogMessage [0x02518937+455]
	content::RTCPeerConnectionHandler::~RTCPeerConnectionHandler [0x023E83C9+641]
	rtc::RefCountedObject<content::`anonymous namespace'::SetSessionDescriptionRequest>::`vector deleting destructor' [0x023E8604+17]
	rtc::RefCountedObject<content::`anonymous namespace'::CreateSessionDescriptionRequest>::Release [0x023EB9C1+23]
	`anonymous namespace'::CreateSessionDescriptionMsg::`vector deleting destructor' [0x01670187+30]
	webrtc::PeerConnection::OnMessage [0x01673D48+154]
	jingle_glue::JingleThreadWrapper::Dispatch [0x034EFC50+131]
	jingle_glue::JingleThreadWrapper::RunTask [0x034F0326+244]
	base::internal::InvokeHelper<1,void>::MakeItSo<void (__thiscall media::AudioRendererImpl::*const &)(enum media::BufferingState),base::WeakPtr<media::AudioRendererImpl>,enum media::BufferingState const &> [0x02425BEF+43]
	base::internal::Invoker<base::internal::BindState<void (__thiscall media::AudioRendererImpl::*)(enum media::BufferingState),base::WeakPtr<media::AudioRendererImpl>,enum media::BufferingState>,void __cdecl(void)>::RunImpl<void (__thiscall media::AudioRende [0x02425C20+38]
	base::internal::Invoker<base::internal::BindState<void (__thiscall media::AudioRendererImpl::*)(enum media::BufferingState),base::WeakPtr<media::AudioRendererImpl>,enum media::BufferingState>,void __cdecl(void)>::Run [0x024266D1+22]
	base::debug::TaskAnnotator::RunTask [0x0258F327+247]
	base::MessageLoop::RunTask [0x025274BB+1211]
	base::MessageLoop::DoWork [0x025266CE+606]
	base::MessagePumpDefault::Run [0x02568348+424]
	base::MessageLoop::RunHandler [0x02526FF7+103]
	base::RunLoop::Run [0x025299E9+41]
	base::Thread::Run [0x02549195+21]
	base::Thread::ThreadMain [0x02549876+454]
	base::PlatformThread::Sleep [0x02533D52+290]
	BaseThreadInitThunk [0x772C7C04+36]
	RtlInitializeExceptionChain [0x775DAB8F+143]
	RtlInitializeExceptionChain [0x775DAB5A+90]
[3608:3100:0713/143206:ERROR:browser_test_utils.cc(170)] Cannot communicate with DOMOperationObserver.
e:\b\build\slave\win_builder\build\src\chrome\browser\media\webrtc_browsertest_base.cc(304): error: Value of: content::ExecuteScriptAndExtractString( tab_contents, javascript, &result)
  Actual: false
Expected: true
e:\b\build\slave\win_builder\build\src\chrome\browser\media\webrtc_browsertest_base.cc(387): error: Value of: ExecuteJavascript( base::StringPrintf("receiveAnswerFromPeer('%s')", answer.c_str()), from_tab)
  Actual: ""
Expected: "ok-accepted-answer"
[3608:3100:0713/143206:INFO:CONSOLE(13)] "Returning [{"candidate":"candidate:278816273 1 udp 2122260223 192.168.195.147 58822 typ host generation 0 ufrag FihN network-id 1","sdpMid":"audio","sdpMLineIndex":0},{"candidate":"candidate:1578998497 1 tcp 1518280447 192.168.195.147 9 typ host tcptype active generation 0 ufrag FihN network-id 1","sdpMid":"audio","sdpMLineIndex":0}] to test.", source: http://127.0.0.1:50855/webrtc/test_functions.js (13)
[93/94] WebRtcBrowserTest.RunsAudioVideoWebRTCCallInTwoTabsWithClonedCertificateRsa (TIMED OUT)