Marked PageArgumentBinder type as Obsolete

src/Microsoft.AspNetCore.Mvc.RazorPages/DependencyInjection/MvcRazorPagesMvcCoreBuilderExtensions.cs

@@ -118,7 +118,9 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAddSingleton<IPageHandlerMethodSelector, DefaultPageHandlerMethodSelector>();
 
             // Page model binding
+#pragma warning disable CS0618 // Type or member is obsolete
             services.TryAddSingleton<PageArgumentBinder, DefaultPageArgumentBinder>();
+#pragma warning restore CS0618 // Type or member is obsolete
 
             // Action executors
             services.TryAddSingleton<PageResultExecutor>();

src/Microsoft.AspNetCore.Mvc.RazorPages/Infrastructure/PageArgumentBinder.cs

@@ -7,6 +7,7 @@ using Microsoft.AspNetCore.Mvc.ModelBinding;
 
 namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 {
+    [Obsolete("This type is obsolete and will be removed in a future version.")]
     public abstract class PageArgumentBinder
     {
         public async Task<object> BindModelAsync(PageContext context, Type type, object @default, string name)

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/DefaultPageArgumentBinder.cs

@@ -9,7 +9,9 @@ using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
 
 namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 {
+#pragma warning disable CS0618 // Type or member is obsolete
     public class DefaultPageArgumentBinder : PageArgumentBinder
+#pragma warning restore CS0618 // Type or member is obsolete
     {
         private readonly ParameterBinder _parameterBinder;
 

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/ExecutorFactoryTest.cs

@@ -327,14 +327,5 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Test.Internal
                 throw new NotImplementedException();
             }
         }
-
-        private class MockBinder : PageArgumentBinder
-        {
-            protected override Task<ModelBindingResult> BindAsync(PageContext context, object value, string name, Type type)
-            {
-                var result = ModelBindingResult.Failed();
-                return Task.FromResult(result);
-            }
-        }
     }
 }

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/PageModelTest.cs

@@ -1942,13 +1942,5 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
                 throw new NotImplementedException();
             }
         }
-
-        private class TestPageArgumentBinder : PageArgumentBinder
-        {
-            protected override Task<ModelBindingResult> BindAsync(PageContext context, object value, string name, Type type)
-            {
-                return Task.FromResult(ModelBindingResult.Success(Guid.NewGuid()));
-            }
-        }
     }
 }