Fix cubemap static preview + remove custom inspector (#2041)

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed lights shadow frustum near and far planes.
 - Fixed motionblur issue when  both color and post-porcessing buffers format are with alpha.  (case 1333592)
 - Fixed an issue where auto baking of ambient and reflection probe done for builtin renderer would cause wrong baking in HDRP.
+- Fixed cubemap static preview not updated when the asset is imported.
 
 ## [7.6.0] - 2021-03-25
 

com.unity.render-pipelines.high-definition/Editor/Lighting/Reflection/HDReflectionProbeEditor.Preview.cs

@@ -5,7 +5,7 @@ namespace UnityEditor.Rendering.HighDefinition
 {
     sealed partial class HDReflectionProbeEditor
     {
-        HDCubemapInspector m_CubemapEditor;
+        Editor m_CubemapEditor;
 
         public override bool HasPreviewGUI()
         {
@@ -22,8 +22,7 @@ public override bool HasPreviewGUI()
             if (ValidPreviewSetup() && m_CubemapEditor == null)
             {
                 Editor editor = m_CubemapEditor;
-                CreateCachedEditor(GetTexture(this, target), typeof(HDCubemapInspector), ref editor);
-                m_CubemapEditor = editor as HDCubemapInspector;
+                m_CubemapEditor = CreateEditor(GetTexture(this, target));
             }
 
             // If having one probe selected we always want preview (to prevent preview window from popping)