Make DefaultTagHelperResolver use the correct GetTagHelpersAsync.

- Prior to this we weren't overriding the `GetTagHelpersAsync` method resulting in our TagHelper discovery being executed in-process.
- Removed legacy `ITagHelperResolver` legacy types.

src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/DefaultProjectSnapshotWorker.cs

@@ -48,7 +48,7 @@ namespace Microsoft.CodeAnalysis.Razor.ProjectSystem
             // Don't block the main thread
             if (_foregroundDispatcher.IsForegroundThread)
             {
-                return Task.Factory.StartNew(ProjectUpdatesCoreAsync, update, CancellationToken.None, TaskCreationOptions.None, _foregroundDispatcher.BackgroundScheduler);
+                return Task.Factory.StartNew(ProjectUpdatesCoreAsync, update, cancellationToken, TaskCreationOptions.None, _foregroundDispatcher.BackgroundScheduler);
             }
 
             return ProjectUpdatesCoreAsync(update);
@@ -63,7 +63,7 @@ namespace Microsoft.CodeAnalysis.Razor.ProjectSystem
             var configuration = await _configurationFactory.GetConfigurationAsync(update.UnderlyingProject);
             update.Configuration = configuration;
 
-            var result = await _tagHelperResolver.GetTagHelpersAsync(update.UnderlyingProject);
+            var result = await _tagHelperResolver.GetTagHelpersAsync(update.UnderlyingProject, CancellationToken.None);
             update.TagHelpers = result.Descriptors;
         }
     }

src/Microsoft.CodeAnalysis.Razor.Workspaces/TagHelperResolver.cs

@@ -11,12 +11,6 @@ namespace Microsoft.CodeAnalysis.Razor
     {
         public abstract TagHelperResolutionResult GetTagHelpers(Compilation compilation);
 
-        public virtual async Task<TagHelperResolutionResult> GetTagHelpersAsync(
+        public abstract Task<TagHelperResolutionResult> GetTagHelpersAsync(Project project, CancellationToken cancellationToken);
-            Project project,
-            CancellationToken cancellationToken = default(CancellationToken))
-        {
-            var compilation = await project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);
-            return GetTagHelpers(compilation);
-        }
     }
 }

src/Microsoft.CodeAnalysis.Remote.Razor/DefaultTagHelperResolver.cs

@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Razor.Extensions;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.CodeAnalysis.Razor;
@@ -42,5 +44,11 @@ namespace Microsoft.CodeAnalysis.Remote.Razor
 
             return resolutionResult;
         }
+
+        public override async Task<TagHelperResolutionResult> GetTagHelpersAsync(Project project, CancellationToken cancellationToken)
+        {
+            var compilation = await project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);
+            return GetTagHelpers(compilation);
+        }
     }
 }

src/Microsoft.VisualStudio.LanguageServices.Razor/DefaultTagHelperResolver.cs

@@ -3,15 +3,12 @@
 
 using System;
 using System.Collections.Generic;
-using System.Composition;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Razor.Extensions;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor;
-using Microsoft.VisualStudio.Shell;
-using Microsoft.VisualStudio.Shell.Interop;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 
@@ -28,7 +25,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor
             _workspace = workspace;
         }
 
-        public async Task<TagHelperResolutionResult> GetTagHelpersAsync(Project project)
+        public override async Task<TagHelperResolutionResult> GetTagHelpersAsync(Project project, CancellationToken cancellationToken)
         {
             if (project == null)
             {
@@ -39,11 +36,9 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor
             {
                 TagHelperResolutionResult result;
 
-                // We're being overly defensive here because the OOP host can return null for the client/session/operation
+                // We're being defensive here because the OOP host can return null for the client/session/operation
                 // when it's disconnected (user stops the process).
-                //
+                var client = await RazorLanguageServiceClientFactory.CreateAsync(_workspace, cancellationToken);
-                // This will change in the future to an easier to consume API but for VS RTM this is what we have.
-                var client = await RazorLanguageServiceClientFactory.CreateAsync(_workspace, CancellationToken.None);
                 if (client != null)
                 {
                     using (var session = await client.CreateSessionAsync(project.Solution))
@@ -53,7 +48,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor
                             var jsonObject = await session.InvokeAsync<JObject>(
                                 "GetTagHelpersAsync",
                                 new object[] { project.Id.Id, "Foo", },
-                                CancellationToken.None).ConfigureAwait(false);
+                                cancellationToken).ConfigureAwait(false);
 
                             result = GetTagHelperResolutionResult(jsonObject);
 
@@ -66,7 +61,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor
                 }
 
                 // The OOP host is turned off, so let's do this in process.
-                var compilation = await project.GetCompilationAsync(CancellationToken.None).ConfigureAwait(false);
+                var compilation = await project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);
                 result = GetTagHelpers(compilation);
                 return result;
             }

src/Microsoft.VisualStudio.LanguageServices.Razor/Legacy/ITagHelperResolver.cs

@@ -1,18 +0,0 @@
-// 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.Threading.Tasks;
-using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.Razor;
-
-namespace Microsoft.VisualStudio.LanguageServices.Razor
-{
-    // ----------------------------------------------------------------------------------------------------
-    // NOTE: This is only here for VisualStudio binary compatibility. This type should not be used; instead
-    // use the Microsoft.CodeAnalysis.Razor variant from Microsoft.CodeAnalysis.Razor.Workspaces
-    // ----------------------------------------------------------------------------------------------------
-    public interface ITagHelperResolver
-    {
-        Task<TagHelperResolutionResult> GetTagHelpersAsync(Project project);
-    }
-}

src/Microsoft.VisualStudio.LanguageServices.Razor/Legacy/LegacyTagHelperResolver.cs

@@ -1,24 +0,0 @@
-// 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.ComponentModel.Composition;
-using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.Razor;
-
-namespace Microsoft.VisualStudio.LanguageServices.Razor
-{
-    // ----------------------------------------------------------------------------------------------------
-    // NOTE: This is only here for VisualStudio binary compatibility. This type should not be used; instead
-    // use TagHelperResolver.
-    // ----------------------------------------------------------------------------------------------------
-    [Export(typeof(ITagHelperResolver))]
-    internal class LegacyTagHelperResolver : DefaultTagHelperResolver, ITagHelperResolver
-    {
-        [ImportingConstructor]
-        public LegacyTagHelperResolver(
-            [Import(typeof(VisualStudioWorkspace))] Workspace workspace)
-            : base(workspace.Services.GetRequiredService<ErrorReporter>(), workspace)
-        {
-        }
-    }
-}

tooling/Microsoft.VisualStudio.RazorExtension/RazorInfo/RazorInfoViewModel.cs

@@ -18,6 +18,7 @@ using Microsoft.VisualStudio.Shell.Interop;
 using Microsoft.VisualStudio.TextManager.Interop;
 using System.IO;
 using Microsoft.CodeAnalysis.Razor;
+using System.Threading;
 
 namespace Microsoft.VisualStudio.RazorExtension.RazorInfo
 {
@@ -177,7 +178,7 @@ namespace Microsoft.VisualStudio.RazorExtension.RazorInfo
                     .Select(reference => reference.Display)
                     .Select(filter => Path.GetFileNameWithoutExtension(filter));
                 var projectFilters = project.AllProjectReferences.Select(filter => solution.GetProject(filter.ProjectId).AssemblyName);
-                var resolutionResult = await _tagHelperResolver.GetTagHelpersAsync(project);
+                var resolutionResult = await _tagHelperResolver.GetTagHelpersAsync(project, CancellationToken.None);
 
                 var files = GetCshtmlDocuments(project);