fix: crash when exiting simple fullscreen on macOS (#20144)

shell/browser/native_window_mac.h

@@ -161,7 +161,7 @@ class NativeWindowMac : public NativeWindow {
   AtomTouchBar* touch_bar() const { return touch_bar_.get(); }
   bool zoom_to_page_width() const { return zoom_to_page_width_; }
   bool fullscreen_window_title() const { return fullscreen_window_title_; }
-  bool simple_fullscreen() const { return always_simple_fullscreen_; }
+  bool always_simple_fullscreen() const { return always_simple_fullscreen_; }
 
  protected:
   // views::WidgetDelegate:

shell/browser/ui/cocoa/atom_ns_window.mm

@@ -178,8 +178,14 @@ bool ScopedDisableResize::disable_resize_ = false;
 }
 
 - (void)toggleFullScreenMode:(id)sender {
-  if (shell_->simple_fullscreen())
-    shell_->SetSimpleFullScreen(!shell_->IsSimpleFullScreen());
+  bool is_simple_fs = shell_->IsSimpleFullScreen();
+  bool always_simple_fs = shell_->always_simple_fullscreen();
+
+  // If we're in simple fullscreen mode and trying to exit it
+  // we need to ensure we exit it properly to prevent a crash
+  // with NSWindowStyleMaskTitled mode
+  if (is_simple_fs || always_simple_fs)
+    shell_->SetSimpleFullScreen(!is_simple_fs);
   else
     [super toggleFullScreen:sender];
 }

spec-main/api-browser-window-spec.ts

@@ -3389,6 +3389,16 @@ describe('BrowserWindow module', () => {
         w.setFullScreen(true)
       })
 
+      it('does not crash when exiting simpleFullScreen', (done) => {
+        const w = new BrowserWindow()
+        w.setSimpleFullScreen(true)
+
+        setTimeout(() => {
+          w.setFullScreen(!w.isFullScreen())
+          done()
+        }, 1000)
+      })
+
       it('should not be changed by setKiosk method', (done) => {
         const w = new BrowserWindow()
         w.once('enter-full-screen', async () => {