[nrf fromlist] [nrfconnect] Add a delay to last fabric remove action

In some cases, a last fabric removal action should be delayed
to avoid race conditions and allow the device to finish all
currently running tasks.

To control the delay use the
CONFIG_CHIP_LAST_FABRIC_REMOVED_SCHEDULE_TIME kconfig.
By default it has been set to 500 ms.

config/nrfconnect/chip-module/Kconfig.features

@@ -304,4 +304,13 @@ choice CHIP_LAST_FABRIC_REMOVED_ACTION
 
 endchoice
 
+config CHIP_LAST_FABRIC_REMOVED_SCHEDULE_TIME
+	int "After removing the last fabric wait defined time [in milliseconds] to perform an action"
+	depends on !CHIP_LAST_FABRIC_REMOVED_NONE
+	default 500
+	help
+	  After removing the last fabric the device will wait for the defined time and then perform
+	  an action chosen by the CHIP_LAST_FABRIC_REMOVED_ACTION option. This schedule will allow for
+	  avoiding race conditions before the device removes non-volatile data.
+
 endif # CHIP

examples/platform/nrfconnect/util/include/FabricTableDelegate.h

@@ -42,19 +42,25 @@ class AppFabricTableDelegate : public chip::FabricTable::Delegate
 #ifndef CONFIG_CHIP_LAST_FABRIC_REMOVED_NONE
         static AppFabricTableDelegate sAppFabricDelegate;
         chip::Server::GetInstance().GetFabricTable().AddFabricDelegate(&sAppFabricDelegate);
+        k_timer_init(&sFactoryResetTimer, &FactoryResetTimerCallback, nullptr);
 #endif // CONFIG_CHIP_LAST_FABRIC_REMOVED_NONE
     }
 
 private:
     void OnFabricRemoved(const chip::FabricTable & fabricTable, chip::FabricIndex fabricIndex)
+    {
+        k_timer_start(&sFactoryResetTimer, K_MSEC(CONFIG_CHIP_LAST_FABRIC_REMOVED_SCHEDULE_TIME), K_NO_WAIT);
+    }
+
+    static void FactoryResetTimerCallback(k_timer * timer)
     {
 #ifndef CONFIG_CHIP_LAST_FABRIC_REMOVED_NONE
         if (chip::Server::GetInstance().GetFabricTable().FabricCount() == 0)
         {
+            chip::DeviceLayer::PlatformMgr().ScheduleWork([](intptr_t) {
 #ifdef CONFIG_CHIP_LAST_FABRIC_REMOVED_ERASE_AND_REBOOT
-            chip::Server::GetInstance().ScheduleFactoryReset();
+                chip::Server::GetInstance().ScheduleFactoryReset();
 #elif defined(CONFIG_CHIP_LAST_FABRIC_REMOVED_ERASE_ONLY) || defined(CONFIG_CHIP_LAST_FABRIC_REMOVED_ERASE_AND_PAIRING_START)
-            chip::DeviceLayer::PlatformMgr().ScheduleWork([](intptr_t) {
                 /* Erase Matter data */
                 chip::DeviceLayer::PersistedStorage::KeyValueStoreMgrImpl().DoFactoryReset();
                 /* Erase Network credentials and disconnect */
@@ -69,9 +75,11 @@ class AppFabricTableDelegate : public chip::FabricTable::Delegate
                 event.Handler = AppTask::StartBLEAdvertisementHandler;
                 AppTask::Instance().PostEvent(event);
 #endif // CONFIG_CHIP_LAST_FABRIC_REMOVED_ERASE_AND_PAIRING_START
-            });
 #endif // CONFIG_CHIP_LAST_FABRIC_REMOVED_ERASE_AND_REBOOT
+            });
         }
 #endif // CONFIG_CHIP_LAST_FABRIC_REMOVED_NONE
     }
+
+    inline static k_timer sFactoryResetTimer;
 };