Merge pull request #808 from github/fixes/usagetracker-dispatcher

Ensure UsageTracker time runs on main thread.

Author: shana

src/GitHub.Exports/Helpers/ThreadingHelper.cs

@@ -7,6 +7,7 @@
 using System.Windows;
 using static Microsoft.VisualStudio.Threading.JoinableTaskFactory;
 using static Microsoft.VisualStudio.Threading.AwaitExtensions;
+using System.Windows.Threading;
 
 namespace GitHub.Helpers
 {
@@ -25,6 +26,11 @@ public static class ThreadingHelper
     {
         public static bool InUIThread => (!Guard.InUnitTestRunner && Application.Current.Dispatcher.CheckAccess()) || !(Guard.InUnitTestRunner);
 
+        /// <summary>
+        /// Gets the Dispatcher for the main thread.
+        /// </summary>
+        public static Dispatcher MainThreadDispatcher => Application.Current.Dispatcher;
+
         /// <summary>
         /// Switch to the UI thread using ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync
         /// Auto-disables switching when running in unit test mode

src/GitHub.VisualStudio/Services/UsageTracker.cs

@@ -65,7 +65,7 @@ public UsageTracker(IGitHubServiceProvider gitHubServiceProvider)
                 TimeSpan.FromMinutes(3),
                 DispatcherPriority.Background,
                 TimerTick,
-                Dispatcher.CurrentDispatcher);
+                ThreadingHelper.MainThreadDispatcher);
 
             RunTimer();
         }