When trying to reproduce a video in the Youtube app,  WAM  crashes in a GBM pixmap buffer initialization with backtrace:

(gdb) bt
#0 0x00007fb0abca4ef8 in ui::GbmPixmapWayland::InitializeBuffer (this=this@entry=0xbfce45a8ae0, size=..., format=format@entry=gfx::BufferFormat::R_8,
usage=usage@entry=gfx::BufferUsage::SCANOUT_CPU_READ_WRITE) at /usr/include/c++/8.2.0/bits/unique_ptr.h:342
#1 0x00007fb0abc9df04 in ui::WaylandSurfaceFactory::CreateNativePixmap (this=0xbfce3ac9c80, widget=<optimized out>, size=..., format=gfx::BufferFormat::R_8,
usage=gfx::BufferUsage::SCANOUT_CPU_READ_WRITE) at ../../git/src/ui/ozone/platform/wayland/wayland_surface_factory.cc:282
#2 0x00007fb0ae71c3aa in gpu::GpuMemoryBufferFactoryNativePixmap::CreateGpuMemoryBuffer (this=0xbfce3c41150, id=..., size=..., format=gfx::BufferFormat::R_8,
usage=gfx::BufferUsage::SCANOUT_CPU_READ_WRITE, client_id=3, surface_handle=0) at ../../git/src/gpu/ipc/service/gpu_memory_buffer_factory_native_pixmap.cc:37
#3 0x00007fb0ae9dafc5 in viz::GpuServiceImpl::CreateGpuMemoryBuffer(gfx::GenericSharedMemoryId, gfx::Size const&, gfx::BufferFormat, gfx::BufferUsage, int, int, base::OnceCallback<void (gfx::GpuMemoryBufferHandle const&)>) (this=<optimized out>, id=..., size=..., format=<optimized out>, usage=<optimized out>, client_id=<optimized out>, surface_handle=0, callback=...)
at /usr/include/c++/8.2.0/bits/unique_ptr.h:342
#4 0x00007fb0abf51d6c in viz::mojom::GpuServiceStubDispatch::AcceptWithResponder (impl=0xbfce3a03b08, message=<optimized out>, responder=...) at ../../git/src/base/callback.h:68
#5 0x00007fb0ae9da6fb in viz::mojom::GpuServiceStub<mojo::RawPtrImplRefTraits<viz::mojom::GpuService> >::AcceptWithResponder (this=<optimized out>, message=<optimized out>, responder=...)
at /usr/include/c++/8.2.0/bits/move.h:74
#6 0x00007fb0ad833459 in mojo::InterfaceEndpointClient::HandleValidatedMessage (this=0xbfce3c66c60, message=0x7fb09fda54c0) at /usr/include/c++/8.2.0/bits/move.h:74
#7 0x00007fb0ad836ad0 in mojo::internal::MultiplexRouter::ProcessIncomingMessage (this=this@entry=0xbfce3b09700, message_wrapper=message_wrapper@entry=0x7fb09fda55d0,
client_call_behavior=client_call_behavior@entry=mojo::internal::MultiplexRouter::ALLOW_DIRECT_CLIENT_CALLS, current_task_runner=0xbfce3ac9eb0) at ../../git/src/mojo/public/cpp/system/message.h:35
#8 0x00007fb0ad83b719 in mojo::internal::MultiplexRouter::Accept (this=0xbfce3b09700, message=0x7fb09fda5780) at ../../git/src/mojo/public/cpp/bindings/connector.h:185
#9 0x00007fb0ad82fdcd in mojo::Connector::ReadSingleMessage (this=this@entry=0xbfce3b09760, read_result=read_result@entry=0x7fb09fda5838) at ../../git/src/mojo/public/cpp/bindings/lib/connector.cc:442
#10 0x00007fb0ad830175 in mojo::Connector::ReadAllAvailableMessages (this=0xbfce3b09760) at ../../git/src/mojo/public/cpp/bindings/lib/connector.cc:472
#11 0x00007fb0ad84a830 in base::RepeatingCallback<void (unsigned int, mojo::HandleSignalsState const&)>::Run(unsigned int, mojo::HandleSignalsState const&) const & (args#1=..., args#0=0,
this=0x7fb09fda58b0) at ../../git/src/base/callback_internal.h:144
#12 mojo::SimpleWatcher::OnHandleReady (this=0xbfce3c601e0, watch_id=<optimized out>, result=0, state=...) at ../../git/src/mojo/public/cpp/system/simple_watcher.cc:274
#13 0x00007fb0ad5faa92 in base::OnceCallback<void ()>::Run() && (this=0x7fb09fda5bc0) at ../../git/src/base/callback_internal.h:144
#14 base::debug::TaskAnnotator::RunTask (this=<optimized out>, queue_function=queue_function@entry=0x7fb0b25d4564 "MessageLoop::PostTask", pending_task=pending_task@entry=0x7fb09fda5bc0)
at ./../../git/src/base/debug/task_annotator.cc:101
#15 0x00007fb0ad619003 in base::internal::IncomingTaskQueue::RunTask (this=<optimized out>, pending_task=pending_task@entry=0x7fb09fda5bc0) at ./../../git/src/base/message_loop/incoming_task_queue.cc:124
#16 0x00007fb0ad61b8de in base::MessageLoop::RunTask (this=this@entry=0xbfce3a7e7e0, pending_task=pending_task@entry=0x7fb09fda5bc0) at ./../../git/src/base/message_loop/message_loop.cc:319
#17 0x00007fb0ad61c6bf in base::MessageLoop::DeferOrRunPendingTask (this=0xbfce3a7e7e0, pending_task=...) at ./../../git/src/base/message_loop/message_loop.cc:329
#18 0x00007fb0ad61c848 in base::MessageLoop::DoWork (this=0xbfce3a7e7e0) at ./../../git/src/base/message_loop/message_loop.cc:373
#19 0x00007fb0ad6a1fd2 in base::MessagePumpLibevent::Run (this=0xbfce3ac18c0, delegate=0xbfce3a7e7e0) at ./../../git/src/base/message_loop/message_pump_libevent.cc:210
#20 0x00007fb0ad64325b in base::RunLoop::Run (this=this@entry=0x7fb09fda5d00) at ./../../git/src/base/run_loop.cc:102
#21 0x00007fb0ad667d61 in base::Thread::Run (run_loop=0x7fb09fda5d00, this=0xbfce3a0ca68) at ./../../git/src/base/threading/thread.cc:255
#22 base::Thread::ThreadMain (this=0xbfce3a0ca68) at ./../../git/src/base/threading/thread.cc:337
#23 0x00007fb0ad69c741 in base::(anonymous namespace)::ThreadFunc (params=<optimized out>) at ./../../git/src/base/threading/platform_thread_posix.cc:76
#24 0x00007fb0aa333ef0 in start_thread (arg=<optimized out>) at pthread_create.c:486
#25 0x00007fb0aa4476ef in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95