Serialize preview mesh in graph asset instead of through GraphInspectorView persistent data

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Data/Graphs/AbstractMaterialGraph.cs

         [NonSerialized]
         List<Guid> m_RemovedProperties = new List<Guid>();
 
+        [SerializeField]
+        SerializableMesh m_PreviewMesh;
+
+        public Mesh previewMesh
+        {
+            get { return m_PreviewMesh.mesh; }
+            set { m_PreviewMesh.mesh = value; }
+        }
+
         public IEnumerable<IShaderProperty> properties
         {
             get { return m_Properties; }

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Inspector/GraphInspectorView.cs

 
 namespace UnityEditor.ShaderGraph.Drawing.Inspector
 {
-    [Serializable]
-    class PersistentMesh
-    {
-        [SerializeField]
-        Mesh m_Mesh;
-
-        public Mesh mesh
-        {
-            get { return m_Mesh; }
-            set { m_Mesh = value; }
-        }
-    }
-
     public class GraphInspectorView : VisualElement, IDisposable
     {
         int m_SelectionHash;
 
         List<INode> m_SelectedNodes;
 
-        PersistentMesh m_PersistentMasterNodePreviewMesh;
-
-            persistenceKey = "GraphInspector";
-
             m_Graph = graph;
             m_SelectedNodes = new List<INode>();
 
             m_PreviewRenderHandle = previewManager.masterRenderData;
             m_PreviewRenderHandle.onPreviewChanged += OnPreviewChanged;
 
+            m_PreviewMeshPicker.SetValueAndNotify(m_Graph.previewMesh);
+
             foreach (var property in m_Graph.properties)
                 m_PropertyItems.Add(new ShaderPropertyView(m_Graph, property));
 
             if (changeEvent.newValue == null)
             {
                 m_PreviewRenderHandle.mesh = null;
-                m_PersistentMasterNodePreviewMesh.mesh = null;
             }
 
             Mesh changedMesh = changeEvent.newValue as Mesh;
                 m_PreviewRenderHandle.mesh = changedMesh;
-                m_PersistentMasterNodePreviewMesh.mesh = changedMesh;
-            SavePersistentData();
-        }
-
-        public override void OnPersistentDataReady()
-        {
-            base.OnPersistentDataReady();
-
-            string key = GetFullHierarchicalPersistenceKey();
-
-            m_PersistentMasterNodePreviewMesh = GetOrCreatePersistentData<PersistentMesh>(m_PersistentMasterNodePreviewMesh, key);
-
-            m_PreviewMeshPicker.SetValueAndNotify(m_PersistentMasterNodePreviewMesh.mesh);
+            m_Graph.previewMesh = changedMesh;
         }
 
         public void UpdateSelection(IEnumerable<INode> nodes)