Avoid redundant repository change events

Previously both TeamExplorerNavigationItemBase and TeamExplorerItemBase
were listring for repository change events. This changes it so that
only TeamExplorerItemBase needs to listen for change events.
TeamExplorerNavigationItemBase needs to subscribe before the item is
visible (the event is required to make it visible).

Author: jcansdale

src/GitHub.TeamFoundation.14/Base/TeamExplorerNavigationItemBase.cs

@@ -1,15 +1,13 @@
 using System;
 using System.Diagnostics;
 using System.Drawing;
-using System.ComponentModel;
 using GitHub.Api;
 using GitHub.Extensions;
 using GitHub.Services;
 using GitHub.UI;
 using GitHub.VisualStudio.Helpers;
 using Microsoft.TeamFoundation.Controls;
 using Microsoft.VisualStudio.PlatformUI;
-using GitHub.Models;
 
 namespace GitHub.VisualStudio.Base
 {
@@ -39,25 +37,8 @@ public TeamExplorerNavigationItemBase(IGitHubServiceProvider serviceProvider,
                 Invalidate();
             };
 
-            UpdateRepoOnMainThread(holder.TeamExplorerContext.ActiveRepository);
-            holder.TeamExplorerContext.PropertyChanged += TeamExplorerContext_PropertyChanged;
-        }
-
-        void TeamExplorerContext_PropertyChanged(object sender, PropertyChangedEventArgs e)
-        {
-            if (e.PropertyName == nameof(holder.TeamExplorerContext.ActiveRepository))
-            {
-                UpdateRepoOnMainThread(holder.TeamExplorerContext.ActiveRepository);
-            }
-        }
-
-        void UpdateRepoOnMainThread(LocalRepositoryModel repo)
-        {
-            holder.JoinableTaskFactory.RunAsync(async () =>
-            {
-                await holder.JoinableTaskFactory.SwitchToMainThreadAsync();
-                UpdateRepo(repo);
-            }).Task.Forget();
+            // Navigation items need to listen for repo change events before they're visible
+            SubscribeToRepoChanges();
         }
 
         public override async void Invalidate()
@@ -73,13 +54,6 @@ void OnThemeChanged()
             Icon = SharedResources.GetDrawingForIcon(octicon, dark ? Colors.DarkThemeNavigationItem : Colors.LightThemeNavigationItem, theme);
         }
 
-        void UpdateRepo(LocalRepositoryModel repo)
-        {
-            ActiveRepo = repo;
-            RepoChanged();
-            Invalidate();
-        }
-
         protected void OpenInBrowser(Lazy<IVisualStudioBrowser> browser, string endpoint)
         {
             var uri = ActiveRepoUri;
@@ -93,25 +67,6 @@ protected void OpenInBrowser(Lazy<IVisualStudioBrowser> browser, string endpoint
             OpenInBrowser(browser, browseUrl);
         }
 
-        void Unsubscribe()
-        {
-            holder.TeamExplorerContext.PropertyChanged -= TeamExplorerContext_PropertyChanged;
-        }
-
-        bool disposed;
-        protected override void Dispose(bool disposing)
-        {
-            if (disposing)
-            {
-                if (!disposed)
-                {
-                    Unsubscribe();
-                    disposed = true;
-                }
-            }
-            base.Dispose(disposing);
-        }
-
         int argbColor;
         public int ArgbColor
         {

src/GitHub.VisualStudio.UI/Base/TeamExplorerItemBase.cs

@@ -30,24 +30,19 @@ public ISimpleApiClient SimpleApiClient
             }
         }
 
-        public TeamExplorerItemBase(IGitHubServiceProvider serviceProvider, ITeamExplorerServiceHolder holder)
-            : base(serviceProvider)
+        public TeamExplorerItemBase(IGitHubServiceProvider serviceProvider, ISimpleApiClientFactory apiFactory,
+            ITeamExplorerServiceHolder holder) : this(serviceProvider, holder)
         {
-            Guard.ArgumentNotNull(serviceProvider, nameof(serviceProvider));
-            Guard.ArgumentNotNull(holder, nameof(holder));
+            Guard.ArgumentNotNull(apiFactory, nameof(apiFactory));
 
-            this.holder = holder;
+            this.apiFactory = apiFactory;
         }
 
-        public TeamExplorerItemBase(IGitHubServiceProvider serviceProvider,
-            ISimpleApiClientFactory apiFactory, ITeamExplorerServiceHolder holder)
+        public TeamExplorerItemBase(IGitHubServiceProvider serviceProvider, ITeamExplorerServiceHolder holder)
             : base(serviceProvider)
         {
-            Guard.ArgumentNotNull(serviceProvider, nameof(serviceProvider));
-            Guard.ArgumentNotNull(apiFactory, nameof(apiFactory));
             Guard.ArgumentNotNull(holder, nameof(holder));
 
-            this.apiFactory = apiFactory;
             this.holder = holder;
         }
 
@@ -63,7 +58,6 @@ public virtual void Initialize(IServiceProvider serviceProvider)
             SubscribeToRepoChanges();
         }
 
-
         public virtual void Execute()
         {
         }
@@ -72,10 +66,15 @@ public virtual void Invalidate()
         {
         }
 
-        void SubscribeToRepoChanges()
+        bool subscribedToRepoChanges = false;
+        protected void SubscribeToRepoChanges()
         {
-            UpdateRepo(holder.TeamExplorerContext.ActiveRepository);
-            holder.TeamExplorerContext.PropertyChanged += TeamExplorerContext_PropertyChanged;
+            if (!subscribedToRepoChanges)
+            {
+                subscribedToRepoChanges = true;
+                UpdateRepoOnMainThread(holder.TeamExplorerContext.ActiveRepository);
+                holder.TeamExplorerContext.PropertyChanged += TeamExplorerContext_PropertyChanged;
+            }
         }
 
         void TeamExplorerContext_PropertyChanged(object sender, PropertyChangedEventArgs e)