chrome ToT on linux desktop
Run chrome --mash
Kill content_browser, which makes the root chrome --mash exit

[2113:2113:0214/171937.812882:961643431047:FATAL:window_tree_client.cc(341)] Check failed: !change->window() || windows_.count(change->window()->server_id()) > 0. 
#0 0x7f4c5ebc9cb7 base::debug::StackTrace::StackTrace()
#1 0x7f4c5ebeaeea logging::LogMessage::~LogMessage()
#2 0x7f4c5a15bc28 aura::WindowTreeClient::ScheduleInFlightChange()
#3 0x7f4c5a15e5fc aura::WindowTreeClient::OnWindowMusRemoveChild()
#4 0x7f4c5a169bc7 aura::Window::~Window()
#5 0x7f4c5a16a2c9 aura::Window::~Window()
#6 0x7f4c5a15a618 aura::WindowTreeClient::~WindowTreeClient()
#7 0x7f4c5a15ade9 aura::WindowTreeClient::~WindowTreeClient()
#8 0x7f4c59654b07 views::MusClient::~MusClient()
#9 0x7f4c59654d29 views::MusClient::~MusClient()
#10 0x7f4c5964b5bf views::AuraInit::~AuraInit()
#11 0x7f4c6003fce1 mash::quick_launch::QuickLaunch::~QuickLaunch()
#12 0x7f4c6003fd79 mash::quick_launch::QuickLaunch::~QuickLaunch()
#13 0x7f4c60b9ca83 service_manager::ServiceContext::~ServiceContext()
#14 0x7f4c60b9cab9 service_manager::ServiceContext::~ServiceContext()
#15 0x7f4c60033214 mash::MashPackagedService::~MashPackagedService()
#16 0x7f4c60b9ca83 service_manager::ServiceContext::~ServiceContext()
#17 0x7f4c5f7e2cd2 MashRunner::StartChildApp()
#18 0x7f4c5f7e424c _ZN4base8internal7InvokerINS0_9BindStateIM10MashRunnerFvN4mojo16InterfaceRequestIN15service_manager5mojom7ServiceEEEEJNS0_17UnretainedWrapperIS3_EEEEEFvS9_EE3RunEPNS0_13BindStateBaseEOS9_
#19 0x7f4c600b1790 service_manager::RunStandaloneService()
#20 0x7f4c5f7e1e47 MashRunner::RunChild()
#21 0x7f4c5f7e1d65 MashRunner::Run()
#22 0x7f4c5f7e2d6c MashMain()
#23 0x7f4c5f7e0240 ChromeMain
#24 0x7f4c55d9ef45 __libc_start_main
#25 0x7f4c5f7e00bd <unknown>

Maybe this needs some kind of code path to trigger an exit if its window is torn down?