File Form missing CMS Usage information

_config/config.yml

@@ -7,6 +7,9 @@ SilverStripe\Admin\LeftAndMain:
 SilverStripe\Assets\File:
   extensions:
     - SilverStripe\CMS\Model\SiteTreeFileExtension
+SilverStripe\AssetAdmin\Forms\FileFormFactory:
+  extensions:
+    - SilverStripe\CMS\Model\SiteTreeFileFormFactoryExtension
 ---
 Name: cmsmodals
 ---

code/Model/SiteTreeFileExtension.php

@@ -41,20 +41,6 @@ class SiteTreeFileExtension extends DataExtension
         'BackLinkHTMLList' => 'HTMLFragment'
     );
 
-    public function updateCMSFields(FieldList $fields)
-    {
-        $fields->insertAfter(
-            'LastEdited',
-            ReadonlyField::create(
-                'BackLinkCount',
-                _t(__CLASS__.'.BACKLINKCOUNT', 'Used on:'),
-                $this->BackLinkTracking()->count() . ' ' . _t(__CLASS__.'.PAGES', 'page(s)')
-            )
-                ->addExtraClass('cms-description-toggle')
-                ->setDescription($this->BackLinkHTMLList())
-        );
-    }
-
     /**
      * Generate an HTML list which provides links to where a file is used.
      *

code/Model/SiteTreeFileFormFactoryExtension.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace SilverStripe\CMS\Model;
+
+use SilverStripe\Assets\File;
+use SilverStripe\Forms\ReadonlyField;
+use SilverStripe\ORM\DataExtension;
+use SilverStripe\Versioned\Versioned;
+
+/**
+ * Extension applied to {@see FileFormFactoryExtension} object to track links to {@see SiteTree} records.
+ *
+ * {@see SiteTreeLinkTracking} for the extension applied to {@see SiteTree}
+ *
+ * Note that since both SiteTree and File are versioned, LinkTracking and ImageTracking will
+ * only be enabled for the Stage record.
+ *
+ * @property File $owner
+ */
+class SiteTreeFileFormFactoryExtension extends DataExtension
+{
+    public function updateForm($form, $controller, $name, $context)
+    {
+        $record = $context['Record'];
+        $fields = $form->Fields();
+
+        $fields->insertAfter(
+            'LastEdited',
+            ReadonlyField::create(
+                'BackLinkCount',
+                _t(__CLASS__.'.BACKLINKCOUNT', 'Used on:'),
+                $record->BackLinkTrackingCount() . ' ' . _t(__CLASS__.'.PAGES', 'page(s)')
+            )
+                ->addExtraClass('cms-description-toggle')
+                ->setDescription($record->BackLinkHTMLList())
+        );
+    }
+}

templates/SilverStripe/CMS/Model/Includes/SiteTreeFileExtension_description.ss

@@ -10,14 +10,14 @@
         <tbody>
         <% loop $BackLinkTracking %>
             <tr>
-				<th>$Pos</th>
+                <td>$Pos</td>
                 <td><a href="$CMSEditLink">$MenuTitle</a></td>
                 <td>
                     $i18n_singular_name
                     <% if $isPublished %>
-						<span class="label label-success">Published</span>
+                        <span class="badge badge-success">Published</span>
                     <% else %>
-						<span class="label label-info">Draft</span>
+                        <span class="badge status-addedtodraft">Draft</span>
                     <% end_if %>
                 </td>
             </tr>