Eliminate WebAssemblyHttpMessageHandler and related code, since this is now built into Mono WebAssembly

Author: SteveSandersonMS

src/Components/Blazor/Blazor/src/Hosting/WebAssemblyHost.cs

@@ -2,11 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Net.Http;
-using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Blazor.Http;
 using Microsoft.AspNetCore.Blazor.Rendering;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.JSInterop;
@@ -30,16 +27,6 @@ public WebAssemblyHost(IServiceProvider services, IJSRuntime runtime)
 
         public Task StartAsync(CancellationToken cancellationToken = default)
         {
-            // We need to do this as early as possible, it eliminates a bunch of problems. Note that what we do
-            // is a bit fragile. If you see things breaking because JSRuntime.Current isn't set, then it's likely
-            // that something on the startup path went wrong.
-            //
-            // We want to the JSRuntime created here to be the 'ambient' runtime when JS calls back into .NET. When
-            // this happens in the browser it will be a direct call from Mono. We effectively needs to set the
-            // JSRuntime in the 'root' execution context which implies that we want to do as part of a direct
-            // call from Program.Main, and before any 'awaits'.
-            SetBrowserHttpMessageHandlerAsDefault();
-
             return StartAsyncAwaited();
         }
 
@@ -102,35 +89,5 @@ public void Dispose()
         {
             (Services as IDisposable)?.Dispose();
         }
-
-        private static void SetBrowserHttpMessageHandlerAsDefault()
-        {
-            // Within the Mono WebAssembly BCL, this is a special private static field
-            // that can be assigned to override the default handler
-            const string getHttpMessageHandlerFieldName = "GetHttpMessageHandler";
-            var getHttpMessageHandlerField = typeof(HttpClient).GetField(
-                getHttpMessageHandlerFieldName,
-                BindingFlags.Static | BindingFlags.NonPublic);
-
-            // getHttpMessageHandlerField will be null in tests, but nonnull when actually
-            // running under Mono WebAssembly
-            if (getHttpMessageHandlerField != null)
-            {
-                // Just in case you're not actually using HttpClient, defer the construction
-                // of the WebAssemblyHttpMessageHandler
-                var handlerSingleton = new Lazy<HttpMessageHandler>(
-                    () => new WebAssemblyHttpMessageHandler());
-                Func<HttpMessageHandler> handlerFactory = () => handlerSingleton.Value;
-                getHttpMessageHandlerField.SetValue(null, handlerFactory);
-            }
-            else
-            {
-                // We log a warning in case this ever happens at runtime (even though there's
-                // no obvious way it could be possible), but don't actually throw because that
-                // would break unit tests
-                Console.WriteLine("WARNING: Could not set default HttpMessageHandler because " +
-                    $"'{getHttpMessageHandlerFieldName}' was not found on '{typeof(HttpClient).FullName}'.");
-            }
-        }
     }
 }

src/Components/Blazor/Blazor/src/Http/FetchCredentialsOption.cs

@@ -1,5 +1,4 @@
 import { navigateTo, internalFunctions as navigationManagerInternalFunctions } from './Services/NavigationManager';
-import { internalFunctions as httpInternalFunctions } from './Services/Http';
 import { attachRootComponentToElement } from './Rendering/Renderer';
 
 // Make the following APIs available in global scope for invocation from JS
@@ -8,7 +7,6 @@ window['Blazor'] = {
 
   _internal: {
     attachRootComponentToElement,
-    http: httpInternalFunctions,
     navigationManager: navigationManagerInternalFunctions,
   },
 };