fix: handle async nature of [NSWindow -toggleFullScreen] (#25470)

shell/browser/ui/cocoa/electron_ns_window.mm

@@ -223,11 +223,23 @@ bool ScopedDisableResize::disable_resize_ = false;
   if (is_simple_fs || always_simple_fs) {
     shell_->SetSimpleFullScreen(!is_simple_fs);
   } else {
-    bool maximizable = shell_->IsMaximizable();
-    [super toggleFullScreen:sender];
+    if (shell_->IsVisible()) {
+      // Until 10.13, AppKit would obey a call to -toggleFullScreen: made inside
+      // windowDidEnterFullScreen & windowDidExitFullScreen. Starting in 10.13,
+      // it behaves as though the transition is still in progress and just emits
+      // "not in a fullscreen state" when trying to exit fullscreen in the same
+      // runloop that entered it. To handle this, invoke -toggleFullScreen:
+      // asynchronously.
+      [super performSelector:@selector(toggleFullScreen:)
+                  withObject:nil
+                  afterDelay:0];
+    } else {
+      [super toggleFullScreen:sender];
+    }
 
     // Exiting fullscreen causes Cocoa to redraw the NSWindow, which resets
     // the enabled state for NSWindowZoomButton. We need to persist it.
+    bool maximizable = shell_->IsMaximizable();
     shell_->SetMaximizable(maximizable);
   }
 }

shell/browser/ui/cocoa/electron_ns_window_delegate.mm

@@ -17,6 +17,8 @@
 #include "ui/views/widget/native_widget_mac.h"
 
 using TitleBarStyle = electron::NativeWindowMac::TitleBarStyle;
+using FullScreenTransitionState =
+    electron::NativeWindowMac::FullScreenTransitionState;
 
 @implementation ElectronNSWindowDelegate
 
@@ -213,23 +215,36 @@ using TitleBarStyle = electron::NativeWindowMac::TitleBarStyle;
 }
 
 - (void)windowWillEnterFullScreen:(NSNotification*)notification {
+  shell_->SetFullScreenTransitionState(FullScreenTransitionState::ENTERING);
+
   shell_->NotifyWindowWillEnterFullScreen();
+
   // Setting resizable to true before entering fullscreen.
   is_resizable_ = shell_->IsResizable();
   shell_->SetResizable(true);
 }
 
 - (void)windowDidEnterFullScreen:(NSNotification*)notification {
+  shell_->SetFullScreenTransitionState(FullScreenTransitionState::NONE);
+
   shell_->NotifyWindowEnterFullScreen();
+
+  shell_->HandlePendingFullscreenTransitions();
 }
 
 - (void)windowWillExitFullScreen:(NSNotification*)notification {
+  shell_->SetFullScreenTransitionState(FullScreenTransitionState::EXITING);
+
   shell_->NotifyWindowWillLeaveFullScreen();
 }
 
 - (void)windowDidExitFullScreen:(NSNotification*)notification {
+  shell_->SetFullScreenTransitionState(FullScreenTransitionState::NONE);
+
   shell_->SetResizable(is_resizable_);
   shell_->NotifyWindowLeaveFullScreen();
+
+  shell_->HandlePendingFullscreenTransitions();
 }
 
 - (void)windowWillClose:(NSNotification*)notification {