Example of a failed build:
https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/linux-chromeos-dbg/builds/4164

 RUN      ] AudioPlayerBrowserTest.OpenAudioOnDrive
[19754:19754:0209/043249.089692:WARNING:user_policy_manager_factory_chromeos.cc(184)] No policy loaded for known non-enterprise user
[19754:19754:0209/043249.161505:WARNING:user_session_manager.cc(1044)] Attempting to save user password for non enterprise user.
[19754:19754:0209/043249.962979:ERROR:network_type_pattern.cc(134)] NetworkTypePattern: wifi: Can not match empty type.
[19754:19754:0209/043249.964699:ERROR:network_type_pattern.cc(134)] NetworkTypePattern: wifi: Can not match empty type.
[19754:19754:0209/043249.967715:ERROR:network_type_pattern.cc(134)] NetworkTypePattern: wifi: Can not match empty type.
[19754:19754:0209/043249.968233:ERROR:network_type_pattern.cc(134)] NetworkTypePattern: wifi: Can not match empty type.
[19754:19754:0209/043251.028971:ERROR:wallpaper_controller.cc(1247)] User is ephemeral or guest! Fallback to default wallpaper.
[19754:19754:0209/043256.114004:INFO:CONSOLE(4988)] "Requesting volume list.", source: chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/background_common_scripts.js (4988)
[19754:19754:0209/043256.252230:INFO:CONSOLE(1164)] "Cache database creating or upgrading.", source: chrome-extension://pmfjbimdmchhbnneeidfognadeopoehp/background_scripts.js (1164)
[19754:19754:0209/043256.303772:INFO:CONSOLE(4990)] "Volume list fetched with: 2 items.", source: chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/background_common_scripts.js (4990)
[19754:19754:0209/043256.306967:INFO:CONSOLE(5000)] "Initializing volume: downloads:Downloads", source: chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/background_common_scripts.js (5000)
[19754:19754:0209/043256.322444:INFO:CONSOLE(5403)] "Requesting file system.", source: chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/background_common_scripts.js (5403)
[19754:19754:0209/043256.980609:INFO:CONSOLE(5000)] "Initializing volume: drive:drive-user", source: chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/background_common_scripts.js (5000)
[19754:19754:0209/043256.981305:INFO:CONSOLE(5403)] "Requesting file system.", source: chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/background_common_scripts.js (5403)
[19754:19754:0209/043257.183343:FATAL:private_api_file_system.cc(809)] Check failed: external_backend->CanHandleType(file_system_url.type()).
#0 0x7f436899264d base::debug::StackTrace::StackTrace()
#1 0x7f4368990c7c base::debug::StackTrace::StackTrace()
#2 0x7f4368a1296d logging::LogMessage::~LogMessage()
#3 0x0000036ffc34 extensions::FileManagerPrivateInternalResolveIsolatedEntriesFunction::RunAsync()
#4 0x000008a3c16d ChromeAsyncExtensionFunction::Run()
#5 0x000003ea92c0 ExtensionFunction::RunWithValidation()
#6 0x000003eafc74 extensions::ExtensionFunctionDispatcher::DispatchWithCallbackInternal()
#7 0x000003eaecbe extensions::ExtensionFunctionDispatcher::Dispatch()
#8 0x000003f186ac extensions::ExtensionWebContentsObserver::OnRequest()
#9 0x000003e2cab2 _ZN3IPC20DispatchToMethodImplIN10extensions21AppWindowContentsImplEMS2_FvPN7content15RenderFrameHostERKNSt3__16vectorINS1_15DraggableRegionENS6_9allocatorIS8_EEEEES4_NS6_5tupleIJSB_EEEJLm0EEEEvPT_T0_PT1_OT2_NS6_16integer_sequenceImJXspT3_EEEE
#10 0x000003e2c9e0 _ZN3IPC16DispatchToMethodIN10extensions21AppWindowContentsImplEN7content15RenderFrameHostEJRKNSt3__16vectorINS1_15DraggableRegionENS5_9allocatorIS7_EEEEENS5_5tupleIJSA_EEEEENS5_9enable_ifIXeqsZT1_sr3std10tuple_sizeINS5_5decayIT2_E4typeEEE5valueEvE4typeEPT_MSM_FvPT0_DpT1_ESP_OSH_
#11 0x000003f18d31 _ZN3IPC8MessageTI29ExtensionHostMsg_Request_MetaNSt3__15tupleIJ31ExtensionHostMsg_Request_ParamsEEEvE8DispatchIN10extensions28ExtensionWebContentsObserverES9_N7content15RenderFrameHostEMS9_FvPSB_RKS4_EEEbPKNS_7MessageEPT_PT0_PT1_T2_
#12 0x000003f1861c extensions::ExtensionWebContentsObserver::OnMessageReceived()
#13 0x000008a3d1ba extensions::ChromeExtensionWebContentsObserver::OnMessageReceived()
#14 0x7f4360ec15a9 content::WebContentsImpl::OnMessageReceived()
#15 0x7f43605342e1 content::RenderFrameHostImpl::OnMessageReceived()
#16 0x7f4360b4fe59 content::RenderProcessHostImpl::OnMessageReceived()
#17 0x7f43640e2f58 IPC::ChannelProxy::Context::OnDispatchMessage()
#18 0x7f43640e8e1f _ZN4base8internal13FunctorTraitsIMN3IPC12ChannelProxy7ContextEFvRKNS2_7MessageEEvE6InvokeIRK13scoped_refptrIS4_EJS7_EEEvS9_OT_DpOT0_
#19 0x7f43640e8d7f _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN3IPC12ChannelProxy7ContextEFvRKNS4_7MessageEEJRK13scoped_refptrIS6_ES9_EEEvOT_DpOT0_
#20 0x7f43640e8d0d _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE7RunImplIRKSA_RKNSt3__15tupleIJSC_S6_EEEJLm0ELm1EEEEvOT_OT0_NSJ_16integer_sequenceImJXspT1_EEEE
#21 0x7f43640e8c1c _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE3RunEPNS0_13BindStateBaseE
#22 0x7f43689435f1 _ZNO4base12OnceCallbackIFvvEE3RunEv
#23 0x7f4368996250 base::debug::TaskAnnotator::RunTask()
#24 0x7f4368a310ea base::internal::IncomingTaskQueue::RunTask()
#25 0x7f4368a398af base::MessageLoop::RunTask()
#26 0x7f4368a39b15 base::MessageLoop::DeferOrRunPendingTask()
#27 0x7f4368a39df3 base::MessageLoop::DoWork()
#28 0x7f4368a3f77b base::MessagePumpLibevent::Run()
#29 0x7f4368a39190 base::MessageLoop::Run()
#30 0x7f4368aef945 base::RunLoop::Run()
#31 0x000006d99ff6 content::RunThisRunLoop()
#32 0x000006d99fbc content::RunMessageLoop()
#33 0x0000024816f0 file_manager::(anonymous namespace)::FileManagerTestListener::GetNextMessage()
#34 0x000002480c67 file_manager::FileManagerBrowserTestBase::RunTestMessageLoop()
#35 0x000002480c17 file_manager::FileManagerBrowserTestBase::StartTest()
#36 0x000002457a89 file_manager::AudioPlayerBrowserTest_OpenAudioOnDrive_Test::RunTestOnMainThread()
#37 0x000006cea4b7 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#38 0x0000009be94d _ZN4base8internal13FunctorTraitsIM25RenderViewContextMenuBaseFvvEvE6InvokeIP21RenderViewContextMenuJEEEvS4_OT_DpOT0_
#39 0x0000009be894 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIM25RenderViewContextMenuBaseFvvEJP21RenderViewContextMenuEEEvOT_DpOT0_
#40 0x000006cec655 _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserTestBaseEFvvEJNS0_17UnretainedWrapperIS4_EEEEEFvvEE7RunImplIRKS6_RKNSt3__15tupleIJS8_EEEJLm0EEEEvOT_OT0_NSF_16integer_sequenceImJXspT1_EEEE
#41 0x000006cec59c _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserTestBaseEFvvEJNS0_17UnretainedWrapperIS4_EEEEEFvvEE3RunEPNS0_13BindStateBaseE
#42 0x0000009a235d _ZNKR4base17RepeatingCallbackIFvvEE3RunEv
#43 0x000005c92c49 ChromeBrowserMainParts::PreMainMessageLoopRunImpl()
#44 0x000005c90efc ChromeBrowserMainParts::PreMainMessageLoopRun()
#45 0x000002f749d4 chromeos::ChromeBrowserMainPartsChromeos::PreMainMessageLoopRun()
#46 0x7f436009cc2c content::BrowserMainLoop::PreMainMessageLoopRun()
#47 0x7f435ef44d1d _ZN4base8internal13FunctorTraitsIMN7content12ChildProcessEFvvEvE6InvokeIPS3_JEEEvS5_OT_DpOT0_
#48 0x7f435ef44c64 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIMN7content12ChildProcessEFvvEJPS5_EEEvOT_DpOT0_
#49 0x7f43600a3e75 _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserMainLoopEFivEJNS0_17UnretainedWrapperIS4_EEEEEFivEE7RunImplIRKS6_RKNSt3__15tupleIJS8_EEEJLm0EEEEiOT_OT0_NSF_16integer_sequenceImJXspT1_EEEE
#50 0x7f43600a3dbc _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserMainLoopEFivEJNS0_17UnretainedWrapperIS4_EEEEEFivEE3RunEPNS0_13BindStateBaseE
#51 0x7f435ee5c02d _ZNKR4base17RepeatingCallbackIFvvEE3RunEv
#52 0x7f4360e3c7ad content::StartupTaskRunner::RunAllTasksNow()
#53 0x7f4360098130 content::BrowserMainLoop::CreateStartupTasks()
#54 0x7f43600a5fb6 content::BrowserMainRunnerImpl::Initialize()
#55 0x7f4360090441 content::BrowserMain()
#56 0x7f4361f34c91 content::RunNamedProcessTypeMain()
#57 0x7f4361f373e2 content::ContentMainRunnerImpl::Run()
#58 0x7f4361f2e995 content::ContentServiceManagerMainDelegate::RunEmbedderProcess()
#59 0x7f435b660263 service_manager::Main()
#60 0x7f4361f33b0b content::ContentMain()
#61 0x000006cea039 content::BrowserTestBase::SetUp()

Regression range according to SoM:
chromium: 535668 - 535681

#2: Regression range link
https://test-results.appspot.com/revision_range?start=535668&end=535681

See also  Issue 804413