Custom Android Application class to know when the app is in the background

CustomAndroidApplication.cs

using System;
using Acr.UserDialogs;
using Android.App;
using Android.Content;
using Android.Content.Res;
using Android.OS;
using Android.Runtime;
using Android.Util;
using Plugin.CurrentActivity;

namespace Whatever
{
	[Application]
	public class CustomAndroidApplication : Application
	{
		public bool IsInBackground => _lifeCycleHandler.IsInBackground;

		private CustomApplicationLifeCycleHandler _lifeCycleHandler;

		public CustomAndroidApplication(IntPtr javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
		{
		}

		public override void OnCreate()
		{
			base.OnCreate();

			_lifeCycleHandler = new CustomApplicationLifeCycleHandler();
			RegisterActivityLifecycleCallbacks(_lifeCycleHandler);
			RegisterComponentCallbacks(_lifeCycleHandler);
		}

		public override void OnTerminate()
		{
			base.OnTerminate();

			UnregisterActivityLifecycleCallbacks(_lifeCycleHandler);
			UnregisterComponentCallbacks(_lifeCycleHandler);
		}
	}

	internal class CustomApplicationLifeCycleHandler : Java.Lang.Object, Application.IActivityLifecycleCallbacks, IComponentCallbacks2
	{
		public bool IsInBackground { get; private set; }

		public void OnActivityStarted(Activity activity)
		{
			CrossCurrentActivity.Current.Activity = activity;
		}

		public void OnActivityCreated(Activity activity, Bundle savedInstanceState)
		{
			CrossCurrentActivity.Current.Activity = activity;
		}

		public void OnActivityResumed(Activity activity)
		{
			CrossCurrentActivity.Current.Activity = activity;

			if (IsInBackground)
			{
				Log.Warn(nameof(OneHourAndroidApplication), "app went to foreground");
				IsInBackground = false;
			}
		}

		public void OnTrimMemory([GeneratedEnum] TrimMemory level)
		{
			if (level == TrimMemory.UiHidden)
			{
				Log.Warn(nameof(OneHourAndroidApplication), "app went to background");
				IsInBackground = true;
			}
		}

		public void OnActivityDestroyed(Activity activity) { }

		public void OnActivityPaused(Activity activity) { }

		public void OnActivitySaveInstanceState(Activity activity, Bundle outState) { }

		public void OnActivityStopped(Activity activity) { }

		public void OnConfigurationChanged(Configuration newConfig) {  }

		public void OnLowMemory() { }
	}
}