[Android App Compat] Can opt out of sending Appearing/Disappearing events on Resume/Pause (#450)

* Add reproduction for 40722

* [Core] Add Android AppCompat PS props ...

... to disable sending Disappearing/Appearing events on Pause/Resume
respectively.

* [Android] Allow user to disable Pause/Resume evts

* Revise repro to use new PS option

* Update docs

1 files changed, 16 insertions, 7 deletions

diff --git a/Xamarin.Forms.Platform.Android/AppCompat/FragmentContainer.cs b/Xamarin.Forms.Platform.Android/AppCompat/FragmentContainer.cs
index 3931e207..432fcd39 100644
--- a/Xamarin.Forms.Platform.Android/AppCompat/FragmentContainer.cs
+++ b/Xamarin.Forms.Platform.Android/AppCompat/FragmentContainer.cs
@@ -2,6 +2,7 @@ using System;
 using Android.OS;
 using Android.Runtime;
 using Android.Views;
+using Xamarin.Forms.PlatformConfiguration.AndroidSpecific.AppCompat;
 using AView = Android.Views.View;
 using Fragment = Android.Support.V4.App.Fragment;
 
@@ -119,18 +120,26 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 
 		public override void OnPause()
 		{
-			Page currentPage = (Application.Current.MainPage as IPageContainer<Page>)?.CurrentPage;
-			if (currentPage == null || currentPage == PageController)
-				PageController?.SendDisappearing();
+			var shouldSendEvent = Application.Current.OnThisPlatform().GetSendDisappearingEventOnPause();
+			if (shouldSendEvent)
+			{
+				Page currentPage = (Application.Current.MainPage as IPageContainer<Page>)?.CurrentPage;
+				if (currentPage == null || currentPage == PageController)
+					PageController?.SendDisappearing();
+			}
 
 			base.OnPause();
 		}
-		
+
 		public override void OnResume()
 		{
-			Page currentPage = (Application.Current.MainPage as IPageContainer<Page>)?.CurrentPage;
-			if (UserVisibleHint && (currentPage == null || currentPage == PageController))
-				PageController?.SendAppearing();
+			var shouldSendEvent = Application.Current.OnThisPlatform().GetSendAppearingEventOnResume();
+			if (shouldSendEvent)
+			{
+				Page currentPage = (Application.Current.MainPage as IPageContainer<Page>)?.CurrentPage;
+				if (UserVisibleHint && (currentPage == null || currentPage == PageController))
+					PageController?.SendAppearing();
+			}
 
 			base.OnResume();
 		}