Remove some explicit locks and replace with assertions the lock is already held

These should only get called as a part of a larger operation that is
already holding the lock; we can assert that directly and then remove
the extra lock statements.

src/VisualStudio/Core/Def/Implementation/ProjectSystem/VisualStudioProject.cs

@@ -435,7 +435,7 @@ private void OnBatchScopeDisposed()
 
                         foreach (var (path, properties) in _metadataReferencesAddedInBatch)
                         {
-                            var projectReference = _workspace.TryCreateConvertedProjectReference(Id, path, properties);
+                            var projectReference = _workspace.TryCreateConvertedProjectReference_NoLock(Id, path, properties);
 
                             if (projectReference != null)
                             {
@@ -459,7 +459,7 @@ private void OnBatchScopeDisposed()
                     // Metadata reference removing...
                     foreach (var (path, properties) in _metadataReferencesRemovedInBatch)
                     {
-                        var projectReference = _workspace.TryRemoveConvertedProjectReference(Id, path, properties);
+                        var projectReference = _workspace.TryRemoveConvertedProjectReference_NoLock(Id, path, properties);
 
                         if (projectReference != null)
                         {
@@ -778,7 +778,7 @@ public void AddMetadataReference(string fullPath, MetadataReferenceProperties pr
                 {
                     _workspace.ApplyChangeToWorkspace(w =>
                     {
-                        var projectReference = _workspace.TryCreateConvertedProjectReference(Id, fullPath, properties);
+                        var projectReference = _workspace.TryCreateConvertedProjectReference_NoLock(Id, fullPath, properties);
 
                         if (projectReference != null)
                         {
@@ -841,7 +841,7 @@ public void RemoveMetadataReference(string fullPath, MetadataReferenceProperties
                 {
                     _workspace.ApplyChangeToWorkspace(w =>
                     {
-                        var projectReference = _workspace.TryRemoveConvertedProjectReference(Id, fullPath, properties);
+                        var projectReference = _workspace.TryRemoveConvertedProjectReference_NoLock(Id, fullPath, properties);
 
                         // If this was converted to a project reference, we have now recorded the removal -- let's remove it here too
                         if (projectReference != null)

src/VisualStudio/Core/Def/Implementation/ProjectSystem/VisualStudioWorkspaceImpl.cs

@@ -1699,51 +1699,53 @@ private void ConvertProjectReferencesToMetadataReferences_NoLock(ProjectId proje
             SetSolutionAndRaiseWorkspaceChanged_NoLock(modifiedSolution, projectIdsChanged);
         }
 
-        public ProjectReference? TryCreateConvertedProjectReference(ProjectId referencingProject, string path, MetadataReferenceProperties properties)
+        public ProjectReference? TryCreateConvertedProjectReference_NoLock(ProjectId referencingProject, string path, MetadataReferenceProperties properties)
         {
-            lock (_gate)
+            // Any conversion to or from project references must be done under the global workspace lock,
+            // since that needs to be coordinated with updating all projects simultaneously.
+            Debug.Assert(Monitor.IsEntered(_gate));
+
+            if (_projectsByOutputPath.TryGetValue(path, out var ids) && ids.Distinct().Count() == 1)
             {
-                if (_projectsByOutputPath.TryGetValue(path, out var ids) && ids.Distinct().Count() == 1)
-                {
-                    var projectIdToReference = ids.First();
+                var projectIdToReference = ids.First();
 
-                    if (CanConvertMetadataReferenceToProjectReference_NoLock(referencingProject, projectIdToReference))
-                    {
-                        var projectReference = new ProjectReference(
-                            projectIdToReference,
-                            aliases: properties.Aliases,
-                            embedInteropTypes: properties.EmbedInteropTypes);
+                if (CanConvertMetadataReferenceToProjectReference_NoLock(referencingProject, projectIdToReference))
+                {
+                    var projectReference = new ProjectReference(
+                        projectIdToReference,
+                        aliases: properties.Aliases,
+                        embedInteropTypes: properties.EmbedInteropTypes);
 
-                        GetReferenceInfo_NoLock(referencingProject).ConvertedProjectReferences.Add((path, projectReference));
+                    GetReferenceInfo_NoLock(referencingProject).ConvertedProjectReferences.Add((path, projectReference));
 
-                        return projectReference;
-                    }
-                    else
-                    {
-                        return null;
-                    }
+                    return projectReference;
                 }
                 else
                 {
                     return null;
                 }
             }
+            else
+            {
+                return null;
+            }
         }
 
-        public ProjectReference? TryRemoveConvertedProjectReference(ProjectId referencingProject, string path, MetadataReferenceProperties properties)
+        public ProjectReference? TryRemoveConvertedProjectReference_NoLock(ProjectId referencingProject, string path, MetadataReferenceProperties properties)
         {
-            lock (_gate)
+            // Any conversion to or from project references must be done under the global workspace lock,
+            // since that needs to be coordinated with updating all projects simultaneously.
+            Debug.Assert(Monitor.IsEntered(_gate));
+
+            var projectReferenceInformation = GetReferenceInfo_NoLock(referencingProject);
+            foreach (var convertedProject in projectReferenceInformation.ConvertedProjectReferences)
             {
-                var projectReferenceInformation = GetReferenceInfo_NoLock(referencingProject);
-                foreach (var convertedProject in projectReferenceInformation.ConvertedProjectReferences)
+                if (convertedProject.path == path &&
+                    convertedProject.projectReference.EmbedInteropTypes == properties.EmbedInteropTypes &&
+                    convertedProject.projectReference.Aliases.SequenceEqual(properties.Aliases))
                 {
-                    if (convertedProject.path == path &&
-                        convertedProject.projectReference.EmbedInteropTypes == properties.EmbedInteropTypes &&
-                        convertedProject.projectReference.Aliases.SequenceEqual(properties.Aliases))
-                    {
-                        projectReferenceInformation.ConvertedProjectReferences.Remove(convertedProject);
-                        return convertedProject.projectReference;
-                    }
+                    projectReferenceInformation.ConvertedProjectReferences.Remove(convertedProject);
+                    return convertedProject.projectReference;
                 }
             }