mash: crash launching V1 app in a tab

On ToT @ #501046 (plus http://crrev.com/c/666288):
(1) Run "chrome --mash" (also with --disable-features=EnableFullscreenAppList for  Issue 763961 )
(2) Open the app list
(3) Open the Chrome Web Store (ensure it'll open as a tab from the context menu)
Expected: The app runs just fine, no crashes.
Actual: The browser shortcut disappears and chrome crashes, stack below.

The shortcut should never be removed; I'll have to investigate why that happens.

[103405:103405:0913/154203.107665:FATAL:chrome_launcher_controller.cc(661)] Check failed: delegate. There should be always be a browser shortcut item.
#0 0x7fef7f19144d base::debug::StackTrace::StackTrace()
#1 0x7fef7f18f9cc base::debug::StackTrace::StackTrace()
#2 0x7fef7f21976d logging::LogMessage::~LogMessage()
#3 0x563da9f0e71e ChromeLauncherController::GetBrowserShortcutLauncherItemController()
#4 0x563daa37e436 BrowserStatusMonitor::UpdateBrowserItemState()
#5 0x563daa38182a BrowserStatusMonitor::LocalWebContentsObserver::DidFinishNavigation()
#6 0x7fef79997ada content::WebContentsImpl::DidFinishNavigation()
#7 0x7fef78fc75b4 content::NavigationHandleImpl::~NavigationHandleImpl()
#8 0x7fef78fc8309 content::NavigationHandleImpl::~NavigationHandleImpl()
#9 0x7fef78fe791f content::NavigatorImpl::DidNavigate()
#10 0x7fef78ff9c11 content::RenderFrameHostImpl::OnDidCommitProvisionalLoad()
#11 0x7fef78ff6511 content::RenderFrameHostImpl::OnMessageReceived()
#12 0x7fef795fb070 content::RenderProcessHostImpl::OnMessageReceived()
#13 0x7fef7d6d1be8 IPC::ChannelProxy::Context::OnDispatchMessage()
#14 0x7fef7d6d7c5f _ZN4base8internal13FunctorTraitsIMN3IPC12ChannelProxy7ContextEFvRKNS2_7MessageEEvE6InvokeIRK13scoped_refptrIS4_EJS7_EEEvS9_OT_DpOT0_
#15 0x7fef7d6d7bbf _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN3IPC12ChannelProxy7ContextEFvRKNS4_7MessageEEJRK13scoped_refptrIS6_ES9_EEEvOT_DpOT0_
#16 0x7fef7d6d7b4d _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE7RunImplIRKSA_RKNSt3__15tupleIJSC_S6_EEEJLm0ELm1EEEEvOT_OT0_NSJ_16integer_sequenceImJXspT1_EEEE
#17 0x7fef7d6d7a5c _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE3RunEPNS0_13BindStateBaseE
#18 0x7fef7f13f521 _ZNO4base12OnceCallbackIFvvEE3RunEv
#19 0x7fef7f195da8 base::debug::TaskAnnotator::RunTask()
#20 0x7fef7f23dfef base::internal::IncomingTaskQueue::RunTask()
#21 0x7fef7f242cd6 base::MessageLoop::RunTask()
#22 0x7fef7f242f37 base::MessageLoop::DeferOrRunPendingTask()
#23 0x7fef7f243c20 base::MessageLoop::DoWork()
#24 0x7fef7f24c0a3 base::MessagePumpLibevent::Run()
#25 0x7fef7f242586 base::MessageLoop::Run()
#26 0x7fef7f2f4097 base::RunLoop::Run()
#27 0x563da5ce40e5 ChromeBrowserMainParts::MainMessageLoopRun()
#28 0x7fef78b84f0b content::BrowserMainLoop::RunMainMessageLoopParts()
#29 0x7fef78b8cbc5 content::BrowserMainRunnerImpl::Run()
#30 0x7fef78b7924b content::BrowserMain()
#31 0x7fef7a6f2bb9 content::RunNamedProcessTypeMain()
#32 0x7fef7a6f5646 content::ContentMainRunnerImpl::Run()
#33 0x7fef7a6f04cd content::ContentServiceManagerMainDelegate::RunEmbedderProcess()
#34 0x7fef7fa89f4c service_manager::Main()
#35 0x7fef7a6f1b0b content::ContentMain()
#36 0x563da346cec4 ChromeMain
#37 0x563da346cd82 main
#38 0x7fef6416af45 __libc_start_main
#39 0x563da346cc64 <unknown>