Add dependency interface and importer implementation

com.unity.shadergraph/Editor/Data/Nodes/AbstractMaterialNode.cs

             var slot = FindSlot<MaterialSlot>(slotId);
             return slot != null && owner.GetEdges(slot.slotReference).Any();
         }
+
+        public virtual void GetSourceAssetDependencies(List<string> paths)
+        {}
     }
 }

com.unity.shadergraph/Editor/Importers/ShaderGraphImporter.cs

 using UnityEditor.Experimental.AssetImporters;
 using UnityEditor.ShaderGraph.Drawing;
 
-[ScriptedImporter(14, ShaderGraphImporter.ShaderGraphExtension)]
+[ScriptedImporter(14, ShaderGraphExtension)]
 public class ShaderGraphImporter : ScriptedImporter
 {
     public const string ShaderGraphExtension = "shadergraph";
         List<PropertyCollector.TextureInfo> configuredTextures;
         string path = ctx.assetPath;
         string shaderString = null;
+        var sourceAssetDependencyPaths = new List<string>();
         var shaderName = Path.GetFileNameWithoutExtension(path);
         try
         {
             if (!string.IsNullOrEmpty(graph.path))
                 shaderName = graph.path + "/" + shaderName;
             shaderString = graph.GetShader(shaderName, GenerationMode.ForReals, out configuredTextures);
+
+            foreach (var node in graph.GetNodes<AbstractMaterialNode>())
+                node.GetSourceAssetDependencies(sourceAssetDependencyPaths);
         }
         catch (Exception)
         {
 
         ctx.AddObjectToAsset("MainAsset", shader);
         ctx.SetMainObject(shader);
+
+        foreach (var sourceAssetDependencyPath in sourceAssetDependencyPaths.Distinct())
+            ctx.DependsOnSourceAsset(sourceAssetDependencyPath);
     }
 }
 

com.unity.shadergraph/Editor/Importers/ShaderSubGraphImporter.cs

+using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 
 [ScriptedImporter(1, "ShaderSubGraph")]
         if (graph == null)
             return;
 
+        var sourceAssetDependencyPaths = new List<string>();
+        foreach (var node in graph.GetNodes<AbstractMaterialNode>())
+            node.GetSourceAssetDependencies(sourceAssetDependencyPaths);
+
+
+
+        foreach (var sourceAssetDependencyPath in sourceAssetDependencyPaths.Distinct())
+            ctx.DependsOnSourceAsset(sourceAssetDependencyPath);
     }
 }