This issue came up while enabling a feature in WebRtcCaptureFromElementBrowserTest.CaptureFromOpaqueCanvas2DHandlesContextLoss and WebRtcCaptureFromElementBrowserTest.CaptureFromCanvas2DHandlesContextLoss tests. This CL just enables use of GpuMemoryBufferVideoFrame for real-time video from WebRTC, i.e. Hangouts.
https://chromium-review.googlesource.com/c/chromium/src/+/963642
[1:1:0327/094048.940675:FATAL:memory_dump_manager.cc(426)] Check failed: (*mdp_iter)->task_runner && (*mdp_iter)->task_runner->RunsTasksInCurrentSequence(). MemoryDumpProvider "ContextProviderCommandBuffer" attempted to unregister itself in a racy way. Please file a crbug.
#0 0x000002e2b9dc base::debug::StackTrace::StackTrace()
#1 0x000002e3f4ab logging::LogMessage::~LogMessage()
#2 0x000002e9be3a base::trace_event::MemoryDumpManager::UnregisterDumpProviderInternal()
#3 0x00000156623e ui::ContextProviderCommandBuffer::~ContextProviderCommandBuffer()
#4 0x00000156645e ui::ContextProviderCommandBuffer::~ContextProviderCommandBuffer()
#5 0x000005c32afd content::GpuVideoAcceleratorFactoriesImpl::ReleaseContextProvider()
#6 0x000002e2c1b4 base::debug::TaskAnnotator::RunTask()
#7 0x0000021a0664 blink::scheduler::internal::ThreadControllerImpl::DoWork()
#8 0x000000f26afb _ZN4base8internal7InvokerINS0_9BindStateIMN5media26AudioDebugRecordingManagerEFvjEJNS_7WeakPtrIS4_EEjEEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#9 0x000002e2c1b4 base::debug::TaskAnnotator::RunTask()
#10 0x000002ed4359 base::internal::IncomingTaskQueue::RunTask()
#11 0x000002e4843b base::MessageLoop::RunTask()
#12 0x000002e487da base::MessageLoop::DeferOrRunPendingTask()
#13 0x000002e48a3c base::MessageLoop::DoWork()
#14 0x000002e49c36 base::MessagePumpDefault::Run()
#15 0x000002e47d69 base::MessageLoop::Run()
#16 0x000002e6aae9 base::RunLoop::Run()
#17 0x000005acebed content::RendererMain()

These test have earlier surfaced some other bugs, see  issue 820437  and  issue 812186 . This one looks different but I wanted to get your opinion as it might be related to earlier issues. GpuVideoAcceleratorFactoriesImpl holds a scoped_refptr<ui::ContextProviderCommandBuffer> and releases on main thread. We also try to unregister MemoryDumpManager() which was registered on context_thread. What this CL does different than before is that it triggers the use of GpuVideoAcceleratorFactoriesImpl for video use case.
https://cs.chromium.org/chromium/src/services/ui/public/cpp/gpu/context_provider_command_buffer.cc?type=cs&l=426
https://cs.chromium.org/chromium/src/base/trace_event/memory_dump_manager.cc?rcl=ac16acd7553a733b4b42ebd53e5cda8f39c04c4d&l=416

kylechar@ can you help with triage?