From 6c4173ff8f966859727ad4989c02638188e78dec Mon Sep 17 00:00:00 2001
From: Jason Malinowski <jason.malinowski@microsoft.com>
Date: Thu, 18 Oct 2018 14:13:07 -0700
Subject: [PATCH] Allow NavigationBarController to handle background thread
 changes

We might disconnect/reconnect on background threads now, so
be ready for that.
---
 .../NavigationBar/NavigationBarController.cs  | 24 +++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/EditorFeatures/Core/Implementation/NavigationBar/NavigationBarController.cs b/src/EditorFeatures/Core/Implementation/NavigationBar/NavigationBarController.cs
index 76891ec92c8..7411e2e95e2 100644
--- a/src/EditorFeatures/Core/Implementation/NavigationBar/NavigationBarController.cs
+++ b/src/EditorFeatures/Core/Implementation/NavigationBar/NavigationBarController.cs
@@ -94,8 +94,6 @@ private void OnWorkspaceRegistrationChanged(object sender, EventArgs e)
 
         private void ConnectToWorkspace(Workspace workspace)
         {
-            AssertIsForeground();
-
             // If we disconnected before the workspace ever connected, just disregard
             if (_disconnected)
             {
@@ -105,8 +103,26 @@ private void ConnectToWorkspace(Workspace workspace)
             _workspace = workspace;
             _workspace.WorkspaceChanged += this.OnWorkspaceChanged;
 
-            // For the first time you open the file, we'll start immediately
-            StartModelUpdateAndSelectedItemUpdateTasks(modelUpdateDelay: 0, selectedItemUpdateDelay: 0, updateUIWhenDone: true);
+            void connectToNewWorkspace()
+            {
+                // For the first time you open the file, we'll start immediately
+                StartModelUpdateAndSelectedItemUpdateTasks(modelUpdateDelay: 0, selectedItemUpdateDelay: 0, updateUIWhenDone: true);
+            }
+
+            if (IsForeground())
+            {
+                connectToNewWorkspace();
+            }
+            else
+            {
+                var asyncToken = _asyncListener.BeginAsyncOperation(nameof(ConnectToWorkspace));
+                Task.Run(async () =>
+                {
+                    await ThreadingContext.JoinableTaskFactory.SwitchToMainThreadAsync();
+
+                    connectToNewWorkspace();
+                }).CompletesAsyncOperation(asyncToken);
+            }
         }
 
         private void DisconnectFromWorkspace()
-- 
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