fix: don't do self-destroy in LibnotifyNotification::Dismiss()

Callers of Notification::Dismiss() assume that the notification
instance is not deleted after the call, but this was not the case
for LibnotifyNotification:
- Destroy() would get `this` deleted.
- notify_notification_close() in portal environment triggers
LibnotifyNotification::OnNotificationClosed(), and finally calls
Destroy()

This patch removes all Destroy() in Dismiss(), and adds a boolean
to tell whether notify_notification_close() is running, to avoid crash
under portal environment.

Fixes #40461.

Co-authored-by: taoky <me@taoky.moe>

shell/browser/notifications/linux/libnotify_notification.cc

@@ -159,21 +159,21 @@ void LibnotifyNotification::Show(const NotificationOptions& options) {
 
 void LibnotifyNotification::Dismiss() {
   if (!notification_) {
-    Destroy();
     return;
   }
 
   GError* error = nullptr;
+  on_dismissing_ = true;
   libnotify_loader_.notify_notification_close(notification_, &error);
   if (error) {
     log_and_clear_error(error, "notify_notification_close");
-    Destroy();
   }
+  on_dismissing_ = false;
 }
 
 void LibnotifyNotification::OnNotificationClosed(
     NotifyNotification* notification) {
-  NotificationDismissed();
+  NotificationDismissed(!on_dismissing_);
 }
 
 void LibnotifyNotification::OnNotificationView(NotifyNotification* notification,

shell/browser/notifications/linux/libnotify_notification.h

@@ -33,6 +33,7 @@ class LibnotifyNotification : public Notification {
   RAW_PTR_EXCLUSION NotifyNotification* notification_ = nullptr;
 
   ScopedGSignal signal_;
+  bool on_dismissing_ = false;
 };
 
 }  // namespace electron