Move Mono.WebAssembly.Interop project into "src" dir to match build conventions

Blazor.sln

@@ -99,7 +99,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.JSInterop", "src\
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.JSInterop.Test", "test\Microsoft.JSInterop.Test\Microsoft.JSInterop.Test.csproj", "{BA1CE1FD-89D8-423F-A21B-6B212674EB39}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Mono.WebAssembly.Interop", "src\mono\Mono.WebAssembly.Interop\Mono.WebAssembly.Interop.csproj", "{C56873E6-8F49-476E-AF51-B5D187832CF5}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Mono.WebAssembly.Interop", "src\Mono.WebAssembly.Interop\Mono.WebAssembly.Interop.csproj", "{C56873E6-8F49-476E-AF51-B5D187832CF5}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

samples/MonoSanityClient/MonoSanityClient.csproj

@@ -11,7 +11,7 @@
 
   <ItemGroup>
     <!-- Share the InternalCalls.cs source here so we get access to the same interop externs -->
-    <Compile Include="..\..\src\mono\Mono.WebAssembly.Interop\InternalCalls.cs" />
+    <Compile Include="..\..\src\Mono.WebAssembly.Interop\InternalCalls.cs" />
   </ItemGroup>
 
 </Project>

src/Microsoft.AspNetCore.Blazor.Browser/Microsoft.AspNetCore.Blazor.Browser.csproj

@@ -10,7 +10,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\Microsoft.AspNetCore.Blazor\Microsoft.AspNetCore.Blazor.csproj" />
-    <ProjectReference Include="..\mono\Mono.WebAssembly.Interop\Mono.WebAssembly.Interop.csproj" />
+    <ProjectReference Include="..\Mono.WebAssembly.Interop\Mono.WebAssembly.Interop.csproj" />
   </ItemGroup>
 
 </Project>

src/Mono.WebAssembly.Interop/InternalCalls.cs

@@ -0,0 +1,25 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Runtime.CompilerServices;
+
+namespace Mono.WebAssembly.Interop
+{
+    /// <summary>
+    /// Methods that map to the functions compiled into the Mono WebAssembly runtime,
+    /// as defined by 'mono_add_internal_call' calls in driver.c
+    /// </summary>
+    internal class InternalCalls
+    {
+        // The exact namespace, type, and method names must match the corresponding entries
+        // in driver.c in the Mono distribution
+
+        // We're passing asyncHandle by ref not because we want it to be writable, but so it gets
+        // passed as a pointer (4 bytes). We can pass 4-byte values, but not 8-byte ones.
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        public static extern string InvokeJSMarshalled(out string exception, ref long asyncHandle, string functionIdentifier, string argsJson);
+
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        public static extern TRes InvokeJSUnmarshalled<T0, T1, T2, TRes>(out string exception, string functionIdentifier, T0 arg0, T1 arg1, T2 arg2);
+    }
+}

src/Mono.WebAssembly.Interop/Mono.WebAssembly.Interop.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Microsoft.JSInterop\Microsoft.JSInterop.csproj" />
+  </ItemGroup>
+
+</Project>

src/Mono.WebAssembly.Interop/MonoWebAssemblyJSRuntime.cs

@@ -0,0 +1,87 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.JSInterop;
+
+namespace Mono.WebAssembly.Interop
+{
+    /// <summary>
+    /// Provides methods for invoking JavaScript functions for applications running
+    /// on the Mono WebAssembly runtime.
+    /// </summary>
+    public class MonoWebAssemblyJSRuntime : JSInProcessRuntimeBase
+    {
+        /// <inheritdoc />
+        protected override string InvokeJS(string identifier, string argsJson)
+        {
+            var noAsyncHandle = default(long);
+            var result = InternalCalls.InvokeJSMarshalled(out var exception, ref noAsyncHandle, identifier, argsJson);
+            return exception != null
+                ? throw new JSException(exception)
+                : result;
+        }
+
+        /// <inheritdoc />
+        protected override void BeginInvokeJS(long asyncHandle, string identifier, string argsJson)
+        {
+            InternalCalls.InvokeJSMarshalled(out _, ref asyncHandle, identifier, argsJson);
+        }
+
+        #region Custom MonoWebAssemblyJSRuntime methods
+
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="TRes">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TRes InvokeUnmarshalled<TRes>(string identifier)
+            => InvokeUnmarshalled<object, object, object, TRes>(identifier, null, null, null);
+
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="T0">The type of the first argument.</typeparam>
+        /// <typeparam name="TRes">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <param name="arg0">The first argument.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TRes InvokeUnmarshalled<T0, TRes>(string identifier, T0 arg0)
+            => InvokeUnmarshalled<T0, object, object, TRes>(identifier, arg0, null, null);
+
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="T0">The type of the first argument.</typeparam>
+        /// <typeparam name="T1">The type of the second argument.</typeparam>
+        /// <typeparam name="TRes">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <param name="arg0">The first argument.</param>
+        /// <param name="arg1">The second argument.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TRes InvokeUnmarshalled<T0, T1, TRes>(string identifier, T0 arg0, T1 arg1)
+            => InvokeUnmarshalled<T0, T1, object, TRes>(identifier, arg0, arg1, null);
+
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="T0">The type of the first argument.</typeparam>
+        /// <typeparam name="T1">The type of the second argument.</typeparam>
+        /// <typeparam name="T2">The type of the third argument.</typeparam>
+        /// <typeparam name="TRes">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <param name="arg0">The first argument.</param>
+        /// <param name="arg1">The second argument.</param>
+        /// <param name="arg2">The third argument.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TRes InvokeUnmarshalled<T0, T1, T2, TRes>(string identifier, T0 arg0, T1 arg1, T2 arg2)
+        {
+            var result = InternalCalls.InvokeJSUnmarshalled<T0, T1, T2, TRes>(out var exception, identifier, arg0, arg1, arg2);
+            return exception != null
+                ? throw new JSException(exception)
+                : result;
+        }
+
+        #endregion
+    }
+}