Mash: External display blank when mirroring, crashes on linux-chromeos

On Chrome OS eve 70.0.3524.0 and ToT @ #584811
(1a) Run chrome --ash-host-window-bounds=800x600,800+0-800x700 --enable-features=Mash
(1b) Use eve or a similar device, enable about:flags "Mash" and attach an external display
(2) Go to chrome://settings/display
(3) Click "Mirror Internal Display" checkbox
Expected: The external/second display mirrors the first.
Actual: Black/blank external display and crash on linux-chromeos

ash:218448:218448:0821/132318.433001:FATAL:mirror_window_controller.cc(190)] Check failed: !host->has_input_method(). 
#0 0x7ff650bb855c base::debug::StackTrace::StackTrace()
#1 0x7ff650aebe5b logging::LogMessage::~LogMessage()
#2 0x7ff64a3e2090 ash::MirrorWindowController::UpdateWindow()
#3 0x7ff64a3f2d7a ash::WindowTreeHostManager::CreateOrUpdateMirroringDisplay()
#4 0x7ff64a8c6375 display::DisplayManager::CreateMirrorWindowIfAny()
#5 0x7ff64a8cd777 _ZN4base8internal7InvokerINS0_9BindStateIMN7display14DisplayManagerEFvvEJNS_7WeakPtrIS4_EEEEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#6 0x7ff650acee25 base::debug::TaskAnnotator::RunTask()
...

[218395:218395:0821/132318.722547:FATAL:extension_function.cc(505)] Check failed: !browser_client || browser_client->IsShuttingDown() || did_respond() || ignore_all_did_respond_for_testing_do_not_use. system.display.getInfo
#0 0x7f59b781855c base::debug::StackTrace::StackTrace()
#1 0x7f59b774be5b logging::LogMessage::~LogMessage()
#2 0x5571500fca62 UIThreadExtensionFunction::~UIThreadExtensionFunction()
#3 0x5571501a756e extensions::AppViewGuestInternalAttachFrameFunction::~AppViewGuestInternalAttachFrameFunction()
#4 0x55715019d644 _ZN4base8internal9BindStateIMN10extensions16AsyncApiFunctionEFvvEJ13scoped_refptrIS3_EEE7DestroyEPKNS0_13BindStateBaseE
#5 0x55714ffc2e37 _ZN4base8internal9BindStateIMN11google_apis26MultipartUploadRequestBaseEFvNS2_17DriveApiErrorCodeERKNS_17RepeatingCallbackIFvvEEENSt3__110unique_ptrINS_5ValueENSA_14default_deleteISC_EEEEEJNS_7WeakPtrIS3_EES4_S7_EE7DestroyEPKNS0_13BindStateBaseE
#6 0x7f59b0b7c11c ash::mojom::CrosDisplayConfigController_GetDisplayLayoutInfo_ForwardToCallback::~CrosDisplayConfigController_GetDisplayLayoutInfo_ForwardToCallback()
#7 0x7f59b7aa6ead std::__1::__tree<>::destroy()
#8 0x7f59b7aa6e8a std::__1::__tree<>::destroy()
#9 0x7f59b7aa6d0c mojo::InterfaceEndpointClient::NotifyError()

Doesn't repro with --enable-features=SingleProcessMash on linux-chromeos