--- /dev/null
+<?php
+
+namespace Drupal\metatag_facebook\Plugin\metatag\Tag;
+
+use \Drupal\metatag\Plugin\metatag\Tag\MetaPropertyBase;
+
+/**
+ * The Facebook "fb:app_id" meta tag.
+ *
+ * @MetatagTag(
+ * id = "fb_app_id",
+ * label = @Translation("Facebook Application ID"),
+ * description = @Translation("A comma-separated list of Facebook Platform Application IDs applicable for this site."),
+ * name = "fb:app_id",
+ * group = "facebook",
+ * weight = 2,
+ * type = "string",
+ * secure = FALSE,
+ * multiple = FALSE
+ * )
+ */
+class FbAppId extends MetaPropertyBase {
+ // Nothing here yet. Just a placeholder class for a plugin.
+}