Assume basline capabilities (#23185)

In a Blazor app, the apply-update capabilities are available after the app is up and running in the browser.
Occasionally it takes long for the app to start up and our baseline task times out. Currently we return an empty
list of capabilities which causes the compiler to produce no deltas. This PR bumps up the timeout ever so slightly
and returns baseline capabilities instead.

Fixes dotnet/aspnetcore#36723

Author: pranavkm

src/BuiltInTools/dotnet-watch/HotReload/BlazorWebAssemblyDeltaApplier.cs

@@ -10,18 +10,17 @@
 using System.Linq;
 using System.Net.WebSockets;
 using System.Text;
-using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.ExternalAccess.Watch.Api;
-using Microsoft.Extensions.HotReload;
 using Microsoft.Extensions.Tools.Internal;
 
 namespace Microsoft.DotNet.Watcher.Tools
 {
     internal class BlazorWebAssemblyDeltaApplier : IDeltaApplier
     {
         private static Task<ImmutableArray<string>>? _cachedCapabilties;
+        private static readonly ImmutableArray<string> _baselineCapabilities = ImmutableArray.Create<string>("Baseline");
         private readonly IReporter _reporter;
         private int _sequenceId;
 
@@ -48,7 +47,7 @@ async Task<ImmutableArray<string>> GetApplyUpdateCapabilitiesCoreAsync()
             {
                 if (context.BrowserRefreshServer is null)
                 {
-                    return ImmutableArray<string>.Empty;
+                    return _baselineCapabilities;
                 }
 
                 await context.BrowserRefreshServer.WaitForClientConnectionAsync(cancellationToken);
@@ -58,14 +57,14 @@ async Task<ImmutableArray<string>> GetApplyUpdateCapabilitiesCoreAsync()
                 var buffer = ArrayPool<byte>.Shared.Rent(32 * 1024);
                 try
                 {
-                    // We'll query the browser and ask it send capabilities. If the browser does not respond in 10s, we'll assume something is amiss and return
-                    // no capabilities. This should give you baseline hot reload capabilties.
+                    // We'll query the browser and ask it send capabilities. If the browser does not respond in a short duration, we'll assume something is amiss and return
+                    // baseline capabilities.
                     var response = await context.BrowserRefreshServer.ReceiveAsync(buffer, cancellationToken)
                         .AsTask()
-                        .WaitAsync(TimeSpan.FromSeconds(10), cancellationToken);
+                        .WaitAsync(TimeSpan.FromSeconds(15), cancellationToken);
                     if (!response.HasValue || !response.Value.EndOfMessage || response.Value.MessageType != WebSocketMessageType.Text)
                     {
-                        return ImmutableArray<string>.Empty;
+                        return _baselineCapabilities;
                     }
 
                     var values = Encoding.UTF8.GetString(buffer.AsSpan(0, response.Value.Count));
@@ -83,7 +82,7 @@ async Task<ImmutableArray<string>> GetApplyUpdateCapabilitiesCoreAsync()
                     ArrayPool<byte>.Shared.Return(buffer);
                 }
 
-                return ImmutableArray<string>.Empty;
+                return _baselineCapabilities;
             }
         }