Remove legacy signature help interaction code.

src/EditorFeatures/Core.Wpf/SignatureHelp/SignatureHelpBeforeCompletionCommandHandler.cs

@@ -20,19 +20,11 @@
 namespace Microsoft.CodeAnalysis.Editor.CommandHandlers
 {
     /// <summary>
-    /// There are two forms of intellisense that may be active at the same time. Completion and
-    /// SigHelp. Completion precedes SigHelp in the command handler because it wants to make sure
-    /// it's operating on a buffer *after* Completion has changed it. i.e. if "WriteL(" is typed,
-    /// sig help wants to allow completion to complete that to "WriteLine(" before it tried to
-    /// proffer sig help. If we were to reverse things, then we'd get a bogus situation where sig
-    /// help would see "WriteL(" would have nothing to offer and would return.
-    /// 
-    /// However, despite wanting sighelp to receive typechar first and then defer it to completion,
-    /// we want completion to receive other events first (like escape, and navigation keys). We
-    /// consider completion to have higher priority for those commands. In order to accomplish that,
-    /// we introduced <see cref="SignatureHelpAfterCompletionCommandHandler"/>
-    /// This command handler then delegates escape, up and down to those command handlers. 
-    /// It is called before <see cref="PredefinedCompletionNames.CompletionCommandHandler"/>.
+    /// There are two forms of intellisense that may be active at the same time. Completion and SigHelp. Completion
+    /// precedes SigHelp in the command handler because it wants to make sure it's operating on a buffer *after*
+    /// Completion has changed it. i.e. if "WriteL(" is typed, sig help wants to allow completion to complete that to
+    /// "WriteLine(" before it tried to proffer sig help. If we were to reverse things, then we'd get a bogus situation
+    /// where sig help would see "WriteL(" would have nothing to offer and would return.
     /// </summary>
     [Export]
     [Export(typeof(ICommandHandler))]

src/EditorFeatures/Core/IntelliSense/AbstractController.cs

@@ -12,6 +12,7 @@
 using Microsoft.VisualStudio.Text.Editor;
 using Roslyn.Utilities;
 using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
+using System.Threading.Tasks;
 
 namespace Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense;
 
@@ -77,11 +78,11 @@ private void OnTextViewClosed(object sender, EventArgs e)
         this.TextView.TextBuffer.PostChanged -= this.OnTextViewBufferPostChanged;
     }
 
-    public TModel WaitForController()
+    public Task WaitForModelComputation_ForTestingPurposesOnlyAsync()
     {
         this.ThreadingContext.ThrowIfNotOnUIThread();
         VerifySessionIsActive();
-        return sessionOpt.WaitForController();
+        return sessionOpt.WaitForModelComputation_ForTestingPurposesOnlyAsync();
     }
 
     void IController<TModel>.OnModelUpdated(TModel result, bool updateController)
@@ -136,26 +137,4 @@ public void StopModelComputation()
         sessionOpt = null;
         localSession.Stop();
     }
-
-    public bool TryHandleEscapeKey()
-    {
-        this.ThreadingContext.ThrowIfNotOnUIThread();
-
-        // Escape simply dismissed a session if it's up. Otherwise let the next thing in the
-        // chain handle us.
-        if (!IsSessionActive)
-        {
-            return false;
-        }
-
-        // If we haven't even computed a model yet, then also send this command to anyone
-        // listening.  It's unlikely that the command was intended for us (as we wouldn't
-        // have even shown ui yet.
-        var handledCommand = sessionOpt.InitialUnfilteredModel != null;
-
-        // In the presence of an escape, we always stop what we're doing.
-        this.StopModelComputation();
-
-        return handledCommand;
-    }
 }

src/EditorFeatures/Core/IntelliSense/ISession.cs

@@ -4,6 +4,8 @@
 
 #nullable disable
 
+using System.Threading.Tasks;
+
 namespace Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense;
 
 internal interface ISession<TModel>
@@ -12,5 +14,5 @@ internal interface ISession<TModel>
 
     void Stop();
 
-    TModel WaitForController();
+    Task WaitForModelComputation_ForTestingPurposesOnlyAsync();
 }

src/EditorFeatures/Core/IntelliSense/ModelComputation.cs

@@ -16,7 +16,7 @@
 
 namespace Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense;
 
-internal class ModelComputation<TModel> where TModel : class
+internal sealed class ModelComputation<TModel> where TModel : class
 {
     #region Fields that can be accessed from either thread
 
@@ -81,23 +81,10 @@ public Task<TModel> ModelTask
         }
     }
 
-    public TModel WaitForController()
-    {
-        ThreadingContext.ThrowIfNotOnUIThread();
-
-        var model = ModelTask.WaitAndGetResult(CancellationToken.None);
-        if (!_notifyControllerTask.IsCompleted)
-        {
-            OnModelUpdated(model, updateController: true);
-
-            // Reset lastTask so controller.OnModelUpdated is only called once
-            _lastTask = Task.FromResult(model);
-        }
-
-        return model;
-    }
+    public Task WaitForModelComputation_ForTestingPurposesOnlyAsync()
+        => ModelTask;
 
-    public virtual void Stop()
+    public void Stop()
     {
         ThreadingContext.ThrowIfNotOnUIThread();
 

src/EditorFeatures/Core/IntelliSense/Session.cs

@@ -5,6 +5,7 @@
 #nullable disable
 
 using System;
+using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
 using Roslyn.Utilities;
 
@@ -52,9 +53,9 @@ public virtual void Stop()
         this.PresenterSession.Dismiss();
     }
 
-    public TModel WaitForController()
+    public Task WaitForModelComputation_ForTestingPurposesOnlyAsync()
     {
         Computation.ThreadingContext.ThrowIfNotOnUIThread();
-        return Computation.WaitForController();
+        return Computation.WaitForModelComputation_ForTestingPurposesOnlyAsync();
     }
 }

src/EditorFeatures/Test2/IntelliSense/CSharpSignatureHelpCommandHandlerTests.vb

@@ -499,7 +499,7 @@ class C
                     state.SendEscape()
                 End If
 
-                state.SendUpKey()
+                state.CurrentSignatureHelpPresenterSession.SelectPreviousItem()
                 Await state.AssertSelectedSignatureHelpItem("void C.M(int i, int j, int k)")
 
                 state.SendTypeChars("1")
@@ -545,7 +545,7 @@ class C
                     state.SendEscape()
                 End If
 
-                state.SendDownKey()
+                state.CurrentSignatureHelpPresenterSession.SelectNextItem()
                 Await state.AssertSelectedSignatureHelpItem("void C.M(int i, string x)")
 
                 state.SendTypeChars("1")
@@ -580,7 +580,7 @@ class C
                 state.SendTypeChars("1, """" ")
                 Await state.AssertSelectedSignatureHelpItem("void C.M(int i, string x)")
 
-                state.SendUpKey()
+                state.CurrentSignatureHelpPresenterSession.SelectPreviousItem()
                 Await state.AssertSelectedSignatureHelpItem("void C.M(int i, int j)")
 
                 state.SendTypeChars(",")