First seen here: https://app.circleci.com/pipelines/github/electron/electron/29873/workflows/923c3f7e-6bea-47bf-93af-a19497f42cf0/jobs/658750

```
Received signal 11 SEGV_MAPERR 07fba4266cd8
0   Electron Framework                  0x000000010a75eeb9 base::debug::CollectStackTrace(void**, unsigned long) + 9
1   Electron Framework                  0x000000010a659533 base::debug::StackTrace::StackTrace() + 19
2   Electron Framework                  0x000000010a75ed81 base::debug::(anonymous namespace)::StackDumpSignalHandler(int, __siginfo*, void*) + 2385
3   libsystem_platform.dylib            0x00007fff6a65f5fd _sigtramp + 29
4   ???                                 0xf6a3c00070001002 0x0 + 17772259662645694466
5   Electron Framework                  0x0000000104faaf35 electron::NativeWindowMac::RedrawTrafficLights() + 53
6   Electron Framework                  0x000000010a6eeefb base::TaskAnnotator::RunTask(char const*, base::PendingTask*) + 411
7   Electron Framework                  0x000000010a70dee7 base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::DoWorkImpl(base::sequence_manager::LazyNow*) + 519
8   Electron Framework                  0x000000010a70db58 base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::DoWork() + 168
9   Electron Framework                  0x000000010a77f651 base::MessagePumpCFRunLoopBase::RunWork() + 65
10  Electron Framework                  0x000000010a7746e2 base::mac::CallWithEHFrame(void () block_pointer) + 10
11  Electron Framework                  0x000000010a77f01f base::MessagePumpCFRunLoopBase::RunWorkSource(void*) + 63
12  CoreFoundation                      0x00007fff30468a54 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
13  CoreFoundation                      0x00007fff304689f3 __CFRunLoopDoSource0 + 103
14  CoreFoundation                      0x00007fff3046880d __CFRunLoopDoSources0 + 209
15  CoreFoundation                      0x00007fff30467529 __CFRunLoopRun + 937
16  CoreFoundation                      0x00007fff30466b23 CFRunLoopRunSpecific + 466
17  HIToolbox                           0x00007fff2f088abd RunCurrentEventLoopInMode + 292
18  HIToolbox                           0x00007fff2f0887d5 ReceiveNextEventCommon + 584
19  HIToolbox                           0x00007fff2f088579 _BlockUntilNextEventMatchingListInModeWithFilter + 64
20  AppKit                              0x00007fff2d6d3c99 _DPSNextEvent + 883
21  AppKit                              0x00007fff2d6d24e0 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1352
22  AppKit                              0x00007fff2d6c41ee -[NSApplication run] + 658
23  Electron Framework                  0x000000010a78060c base::MessagePumpNSApplication::DoRun(base::MessagePump::Delegate*) + 348
24  Electron Framework                  0x000000010a77eb22 base::MessagePumpCFRunLoopBase::Run(base::MessagePump::Delegate*) + 130
25  Electron Framework                  0x000000010a70e71d base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::Run(bool, base::TimeDelta) + 349
26  Electron Framework                  0x000000010a6c206c base::RunLoop::Run() + 956
27  Electron Framework                  0x0000000109025f8b content::BrowserMainLoop::RunMainMessageLoopParts() + 203
28  Electron Framework                  0x0000000109028352 content::BrowserMainRunnerImpl::Run() + 82
29  Electron Framework                  0x0000000109022aab content::BrowserMain(content::MainFunctionParams const&) + 267
30  Electron Framework                  0x0000000108e3896e content::ContentMainRunnerImpl::RunServiceManager(content::MainFunctionParams&, bool) + 1406
31  Electron Framework                  0x0000000108e383c3 content::ContentMainRunnerImpl::Run(bool) + 467
32  Electron Framework                  0x000000010ce9225e service_manager::Main(service_manager::MainParams const&) + 3310
33  Electron Framework                  0x0000000106d6f708 content::ContentMain(content::ContentMainParams const&) + 120
34  Electron Framework                  0x0000000104e62486 ElectronMain + 134
35  Electron                            0x0000000103d6f551 main + 289
36  libdyld.dylib                       0x00007fff6a462cc9 start + 1
37  ???                                 0x0000000000000024 0x0 + 36
[end of stack trace]
```

No reliable repro yet but will update when one is found. Potentially happening near this test? https://github.com/electron/electron/blob/0d2e9679600bc757eeb34356dc9c3779d0edccee/spec-main/api-native-theme-spec.ts#L91-L95

cc @MarshallOfSound 
shell/browser/native_window_mac.h
void SetSimpleFullScreen(bool simple_fullscreen) override;
  bool IsSimpleFullScreen() override;
  void SetKiosk(bool kiosk) override;
  bool IsKiosk() override;
  void SetBackgroundColor(SkColor color) override;
  SkColor GetBackgroundColor() override;
  void SetHasShadow(bool has_shadow) override;
  bool HasShadow() override;
  void SetOpacity(const double opacity) override;
  double GetOpacity() override;
  void SetRepresentedFilename(const std::string& filename) override;
  std::string GetRepresentedFilename() override;
  void SetDocumentEdited(bool edited) override;
  bool IsDocumentEdited() override;
  void SetIgnoreMouseEvents(bool ignore, bool forward) override;
  void SetContentProtection(bool enable) override;
  void SetFocusable(bool focusable) override;
  void AddBrowserView(NativeBrowserView* browser_view) override;
  void RemoveBrowserView(NativeBrowserView* browser_view) override;
  void SetParentWindow(NativeWindow* parent) override;
  content::DesktopMediaID GetDesktopMediaID() const override;
  gfx::NativeView GetNativeView() const override;
  gfx::NativeWindow GetNativeWindow() const override;
  gfx::AcceleratedWidget GetAcceleratedWidget() const override;
  NativeWindowHandle GetNativeWindowHandle() const override;
  void SetProgressBar(double progress, const ProgressState state) override;
  void SetOverlayIcon(const gfx::Image& overlay,
                      const std::string& description) override;
  void SetVisibleOnAllWorkspaces(bool visible,
                                 bool visibleOnFullScreen) override;