Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/wordpress-seo-premium/classes/social-previews.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * WPSEO Premium plugin file.
+ *
+ * @package WPSEO\Premium
+ */
+
+/**
+ * Initializer for the social previews.
+ */
+class WPSEO_Social_Previews implements WPSEO_WordPress_Integration {
+
+	/**
+	 * Registers the hooks.
+	 *
+	 * @codeCoverageIgnore Method uses dependencies.
+	 *
+	 * @return void
+	 */
+	public function register_hooks() {
+		add_action( 'admin_enqueue_scripts', [ $this, 'enqueue_assets' ] );
+	}
+
+	/**
+	 * Enqueues the javascript and css files needed for the social previews.
+	 *
+	 * @codeCoverageIgnore Method uses dependencies.
+	 *
+	 * @return void
+	 */
+	public function enqueue_assets() {
+		wp_enqueue_script( 'yoast-social-metadata-previews' );
+	}
+}