Chrome Version: 60.0.3101.0

The WebRtcCaptureFromElementBrowserTest.VerifyCanvasCaptureOffscreenCanvasCommitFrames test seems to be flaking (timing out) more than half the time on the "Linux ChromiumOS Tests (dbg)" builder (it seems fine on the release builder):
  https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29?numbuilds=100

More often than not, the builder passes on retry, but has gone red twice today because of this.  Here's one:
  https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/26147

As far as I could find, the first instance of this flake was in
  https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/26139
which was earlier today (it has appeared in about 2/3 of the builds since then).  I don't know this part of the code well enough to locate an likely culprit CL, but it's probably been in the last 24 hours or so.  Additionally, while I couldn't reproduce this locally with yesterday's code, I could with today's code.


Here's the log output from content_browsertests / stdout :

[0517/102517.115801:ERROR:kill_posix.cc(84)] Unable to terminate process group 30244: No such process
[ RUN      ] WebRtcCaptureFromElementBrowserTest.VerifyCanvasCaptureOffscreenCanvasCommitFrames
Xlib:  extension "RANDR" missing on display ":99".
[30244:30244:0517/102433.495007:10934818611:ERROR:proxy_service.cc(1534)] ProxyConfigService for ChromeOS should be created in profile_io_data.cc::CreateProxyConfigService and this should be used only for examples.
BrowserTestBase received signal: Terminated. Backtrace:
#0 0x7efff70721bb base::debug::StackTrace::StackTrace()
#1 0x7efff7070efc base::debug::StackTrace::StackTrace()
#2 0x0000013d3237 content::(anonymous namespace)::DumpStackTraceSignalHandler()
#3 0x7effeabfdcb0 <unknown>
#4 0x7effeacb784d __poll
#5 0x7effe93f9fe4 <unknown>
#6 0x7effe93fa0ec g_main_context_iteration
#7 0x7efff71132af base::MessagePumpGlib::Run()
#8 0x7efff710184d base::MessageLoop::RunHandler()
#9 0x7efff719fd44 base::RunLoop::Run()
#10 0x00000142c896 content::RunThisRunLoop()
#11 0x00000142d4f1 content::MessageLoopRunner::Run()
#12 0x0000013daa3a content::DOMMessageQueue::WaitForMessage()
#13 0x0000013d8c90 content::(anonymous namespace)::ExecuteScriptHelper()
#14 0x0000013d8a70 content::ExecuteScriptAndExtractString()
#15 0x000000af9105 content::WebRtcContentBrowserTestBase::ExecuteJavascriptAndReturnResult()
#16 0x000000af93d4 content::WebRtcContentBrowserTestBase::ExecuteJavascriptAndWaitForOk()
#17 0x000000af9391 content::WebRtcContentBrowserTestBase::MakeTypicalCall()
#18 0x000000aec2c2 content::WebRtcCaptureFromElementBrowserTest_VerifyCanvasCaptureOffscreenCanvasCommitFrames_Test::RunTestOnMainThread()
#19 0x0000013d2f27 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#20 0x000000621b95 _ZN4base8internal13FunctorTraitsIMN7content21CrossSiteTransferTestEFvvEvE6InvokeIPS3_JEEEvS5_OT_DpOT0_
#21 0x000000621ab1 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN7content21CrossSiteTransferTestEFvvEJPS5_EEEvOT_DpOT0_
#22 0x0000013d4b07 _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserTestBaseEFvvEJNS0_17UnretainedWrapperIS4_EEEEEFvvEE7RunImplIRKS6_RKSt5tupleIJS8_EEJLm0EEEEvOT_OT0_NS_13IndexSequenceIJXspT1_EEEE
#23 0x0000013d4a4c _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserTestBaseEFvvEJNS0_17UnretainedWrapperIS4_EEEEEFvvEE3RunEPNS0_13BindStateBaseE
#24 0x000000603add _ZNKR4base8CallbackIFvvELNS_8internal8CopyModeE1ELNS2_10RepeatModeE1EE3RunEv
#25 0x00000152d770 content::ShellBrowserMainParts::PreMainMessageLoopRun()
#26 0x7efff8d6ecd1 content::BrowserMainLoop::PreMainMessageLoopRun()
#27 0x7efff80529a5 _ZN4base8internal13FunctorTraitsIMN7content13URLLoaderImplEFvvEvE6InvokeIPS3_JEEEvS5_OT_DpOT0_
#28 0x7efff8d77e81 _ZN4base8internal12InvokeHelperILb0EiE8MakeItSoIRKMN7content15BrowserMainLoopEFivEJPS5_EEEiOT_DpOT0_
#29 0x7efff8d77e27 _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserMainLoopEFivEJNS0_17UnretainedWrapperIS4_EEEEEFivEE7RunImplIRKS6_RKSt5tupleIJS8_EEJLm0EEEEiOT_OT0_NS_13IndexSequenceIJXspT1_EEEE
#30 0x7efff8d77d6c _ZN4base8internal7InvokerINS0_9BindStateIMN7content15BrowserMainLoopEFivEJNS0_17UnretainedWrapperIS4_EEEEEFivEE3RunEPNS0_13BindStateBaseE
#31 0x7efff80268cd _ZNKR4base8CallbackIFvvELNS_8internal8CopyModeE1ELNS2_10RepeatModeE1EE3RunEv
#32 0x7efff98e784b content::StartupTaskRunner::RunAllTasksNow()
#33 0x7efff8d6c8f0 content::BrowserMainLoop::CreateStartupTasks()
#34 0x7efff8d7b0d7 content::BrowserMainRunnerImpl::Initialize()
#35 0x0000014de18b ShellBrowserMain()
#36 0x0000014c41d5 content::ShellMainDelegate::RunProcess()
#37 0x7efffa5ce9cd content::RunNamedProcessTypeMain()
#38 0x7efffa5d0aef content::ContentMainRunnerImpl::Run()
#39 0x7efffa5cd69a content::ContentServiceManagerMainDelegate::RunEmbedderProcess()
#40 0x7effe7675ef7 service_manager::Main()
#41 0x7efffa5ce52b content::ContentMain()
#42 0x0000013d2c4f content::BrowserTestBase::SetUp()
#43 0x0000013c02d8 content::ContentBrowserTest::SetUp()
#44 0x000000af9020 content::WebRtcContentBrowserTestBase::SetUp()
#45 0x000000d6ad0e testing::internal::HandleSehExceptionsInMethodIfSupported<>()
#46 0x000000d5ccb2 testing::internal::HandleExceptionsInMethodIfSupported<>()
#47 0x000000d51b84 testing::Test::Run()
#48 0x000000d5230d testing::TestInfo::Run()
#49 0x000000d528af testing::TestCase::Run()
#50 0x000000d57c5c testing::internal::UnitTestImpl::RunAllTests()
#51 0x000000d6e88e testing::internal::HandleSehExceptionsInMethodIfSupported<>()
#52 0x000000d5e452 testing::internal::HandleExceptionsInMethodIfSupported<>()
#53 0x000000d578ff testing::UnitTest::Run()
#54 0x00000147c6f1 RUN_ALL_TESTS()
#55 0x00000147b472 base::TestSuite::Run()
#56 0x0000013cbb62 content::ContentTestLauncherDelegate::RunTestSuite()
#57 0x0000014237b2 content::LaunchTests()
#58 0x0000013cb9b8 main
#59 0x7effeabe8f45 __libc_start_main
#60 0x00000059af64 <unknown>
[806/983] WebRtcCaptureFromElementBrowserTest.VerifyCanvasCaptureOffscreenCanvasCommitFrames (TIMED OUT)


emircan@ - could you take a look at this or triage it to the appropriate person?  Thanks!