Switch Json's PooledByteBufferWriter to shared ArrayBuffer helper

src/libraries/Common/src/System/Text/Json/PooledByteBufferWriter.cs

@@ -76,11 +76,7 @@ public override Span<byte> GetSpan(int sizeHint = MinimumBufferSize)
         public override async ValueTask<FlushResult> FlushAsync(CancellationToken cancellationToken = default)
         {
             Debug.Assert(_stream is not null);
-#if NET
             await _stream.WriteAsync(WrittenMemory, cancellationToken).ConfigureAwait(false);
-#else
-            await _stream.WriteAsync(_buffer.DangerousGetUnderlyingBuffer(), _buffer.ActiveStartOffset, _buffer.ActiveLength, cancellationToken).ConfigureAwait(false);
-#endif
             Clear();
 
             return new FlushResult(isCanceled: false, isCompleted: false);

src/libraries/Common/tests/System/Net/Http/DefaultCredentialsTest.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.IO;
 using System.Security.Principal;
 using System.Threading.Tasks;
 

src/libraries/System.IO.Pipelines/src/System.IO.Pipelines.csproj

@@ -52,10 +52,10 @@ System.IO.Pipelines.PipeReader</PackageDescription>
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
-    <Compile Include="System\IO\Pipelines\StreamExtensions.netstandard.cs" />
     <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.netstandard.cs" />
     <Compile Include="System\IO\Pipelines\CancellationTokenExtensions.netstandard.cs" />
 
+    <Compile Include="$(CommonPath)System\IO\StreamExtensions.netstandard.cs" Link="Common\System\IO\StreamExtensions.netstandard.cs" />
     <Compile Include="$(CommonPath)System\Threading\Tasks\TaskToAsyncResult.cs" Link="Common\System\Threading\Tasks\TaskToAsyncResult.cs" />
   </ItemGroup>
 

src/libraries/System.Net.Http.WinHttpHandler/tests/FunctionalTests/System.Net.Http.WinHttpHandler.Functional.Tests.csproj

@@ -14,6 +14,8 @@
     <Compile Include="ServerCertificateTest.cs" />
     <Compile Include="WinHttpHandlerTest.cs" />
     <Compile Include="XunitTestAssemblyAttributes.cs" />
+    <Compile Include="$(CommonPath)System\IO\StreamExtensions.netstandard.cs"
+             Link="Common\System\IO\StreamExtensions.netstandard.cs" />
     <Compile Include="$(CommonPath)\System\Net\Http\HttpHandlerDefaults.cs"
              Link="Common\System\Net\Http\HttpHandlerDefaults.cs" />
     <Compile Include="$(CommonTestPath)System\IO\DelegateStream.cs"
@@ -40,8 +42,6 @@
              Link="Common\System\Net\VerboseTestLogging.cs" />
     <Compile Include="$(CommonTestPath)System\Net\TestWebProxies.cs"
              Link="Common\System\Net\TestWebProxies.cs" />
-    <Compile Include="$(CommonTestPath)System\Net\StreamArrayExtensions.cs"
-             Link="Common\System\Net\StreamArrayExtensions.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Http\ByteAtATimeContent.cs"
              Link="Common\System\Net\Http\ByteAtATimeContent.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Http\ChannelBindingAwareContent.cs"

src/libraries/System.Net.ServerSentEvents/src/System.Net.ServerSentEvents.csproj

@@ -24,6 +24,7 @@ System.Net.ServerSentEvents.SseParser</PackageDescription>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <Compile Include="$(CoreLibSharedDir)System\Runtime\CompilerServices\IsExternalInit.cs" />
+    <Compile Include="$(CommonPath)System\IO\StreamExtensions.netstandard.cs" Link="Common\System\IO\StreamExtensions.netstandard.cs" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">

src/libraries/System.Net.ServerSentEvents/src/System/Net/ServerSentEvents/Helpers.cs

@@ -4,11 +4,7 @@
 using System.Buffers;
 using System.Diagnostics;
 using System.Globalization;
-using System.IO;
-using System.Runtime.InteropServices;
 using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
 
 namespace System.Net.ServerSentEvents
 {
@@ -67,34 +63,5 @@ public static unsafe void WriteUtf8String(this IBufferWriter<byte> writer, ReadO
 
         public static bool ContainsLineBreaks(this ReadOnlySpan<char> text) =>
             text.IndexOfAny('\r', '\n') >= 0;
-
-#if !NET
-
-        public static ValueTask WriteAsync(this Stream stream, ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default)
-        {
-            if (MemoryMarshal.TryGetArray(buffer, out ArraySegment<byte> segment))
-            {
-                return new ValueTask(stream.WriteAsync(segment.Array, segment.Offset, segment.Count, cancellationToken));
-            }
-            else
-            {
-                return WriteAsyncUsingPooledBuffer(stream, buffer, cancellationToken);
-
-                static async ValueTask WriteAsyncUsingPooledBuffer(Stream stream, ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken)
-                {
-                    byte[] sharedBuffer = ArrayPool<byte>.Shared.Rent(buffer.Length);
-                    buffer.Span.CopyTo(sharedBuffer);
-                    try
-                    {
-                        await stream.WriteAsync(sharedBuffer, 0, buffer.Length, cancellationToken).ConfigureAwait(false);
-                    }
-                    finally
-                    {
-                        ArrayPool<byte>.Shared.Return(sharedBuffer);
-                    }
-                }
-            }
-        }
-#endif
     }
 }

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -383,6 +383,7 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+    <Compile Include="$(CommonPath)System\IO\StreamExtensions.netstandard.cs" Link="Common\System\IO\StreamExtensions.netstandard.cs" />
     <Compile Include="System\Collections\Generic\StackExtensions.netstandard.cs" />
     <Compile Include="$(CommonPath)System\Buffers\ArrayBufferWriter.cs" Link="Common\System\Buffers\ArrayBufferWriter.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\StringSyntaxAttribute.cs" />