Fold telemetry listener creation to non-platform specific code

Now the telemetry daemon listener is not platform specific, and there is
only one listener for telemetry, we can remove the API from
`GVFSPlatform` and just construct the `TelemetryDaemonEL` in the
`JsonTracer`.

GVFS/GVFS.Common/GVFSPlatform.cs

@@ -51,8 +51,6 @@ namespace GVFS.Common
         public abstract bool TryGetGVFSHooksPathAndVersion(out string hooksPaths, out string hooksVersion, out string error);
         public abstract bool TryInstallGitCommandHooks(GVFSContext context, string executingDirectory, string hookName, string commandHookPath, out string errorMessage);
 
-        public abstract IEnumerable<EventListener> CreateTelemetryListeners(string providerName, string enlistmentId, string mountId);
-
         public abstract bool TryVerifyAuthenticodeSignature(string path, out string subject, out string issuer, out string error);
 
         public abstract Dictionary<string, string> GetPhysicalDiskInfo(string path, bool sizeStatsOnly);

GVFS/GVFS.Common/Tracing/JsonTracer.cs

@@ -44,8 +44,20 @@ namespace GVFS.Common.Tracing
         {
             if (!disableTelemetry)
             {
-                IEnumerable<EventListener> telemetryListeners = GVFSPlatform.Instance.CreateTelemetryListeners(providerName, enlistmentId, mountId);
-                this.listeners.AddRange(telemetryListeners);
+                string gitBinRoot = GVFSPlatform.Instance.GitInstallation.GetInstalledGitBinPath();
+
+                // If we do not have a git binary, then we cannot check if we should set up telemetry
+                // We also cannot log this, as we are setting up tracer.
+                if (string.IsNullOrEmpty(gitBinRoot))
+                {
+                    return;
+                }
+
+                TelemetryDaemonEventListener daemonListener = TelemetryDaemonEventListener.CreateIfEnabled(gitBinRoot, providerName, enlistmentId, mountId);
+                if (daemonListener != null)
+                {
+                    this.listeners.Add(daemonListener);
+                }
             }
         }
 

GVFS/GVFS.Platform.Mac/MacPlatform.cs

@@ -89,17 +89,6 @@ namespace GVFS.Platform.Mac
             return pipe;
         }
 
-        public override IEnumerable<EventListener> CreateTelemetryListeners(string providerName, string enlistmentId, string mountId)
-        {
-            string gitBinRoot = this.GitInstallation.GetInstalledGitBinPath();
-
-            TelemetryDaemonEventListener daemonListener = TelemetryDaemonEventListener.CreateIfEnabled(gitBinRoot, providerName, enlistmentId, mountId);
-            if (daemonListener != null)
-            {
-                yield return daemonListener;
-            }
-        }
-
         public override string GetCurrentUser()
         {
             throw new NotImplementedException();

GVFS/GVFS.Platform.Windows/WindowsPlatform.cs

@@ -75,24 +75,6 @@ namespace GVFS.Platform.Windows
             return true;
         }
 
-        public override IEnumerable<EventListener> CreateTelemetryListeners(string providerName, string enlistmentId, string mountId)
-        {
-            string gitBinRoot = this.GitInstallation.GetInstalledGitBinPath();
-
-            // If we do not have a git binary, then we cannot check if we should set up telemetry
-            // We also cannot log this, as we are setting up tracer.
-            if (string.IsNullOrEmpty(gitBinRoot))
-            {
-                yield break;
-            }
-
-            TelemetryDaemonEventListener daemonListener = TelemetryDaemonEventListener.CreateIfEnabled(gitBinRoot, providerName, enlistmentId, mountId);
-            if (daemonListener != null)
-            {
-                yield return daemonListener;
-            }
-        }
-
         public override void InitializeEnlistmentACLs(string enlistmentPath)
         {
             // The following permissions are typically present on deskop and missing on Server

GVFS/GVFS.UnitTests/Mock/Common/MockPlatform.cs

@@ -58,11 +58,6 @@ namespace GVFS.UnitTests.Mock.Common
             throw new NotSupportedException();
         }
 
-        public override IEnumerable<EventListener> CreateTelemetryListeners(string providerName, string enlistmentId, string mountId)
-        {
-            yield return new MockListener(EventLevel.Verbose, Keywords.Telemetry);
-        }
-
         public override string GetCurrentUser()
         {
             throw new NotSupportedException();