Customizer: Introduce `customize_loaded_components` filter to allow core components to be disabled.

Also move style rule from `customize-nav-menus.css` to `customize-controls.css` so that widgets button is properly styled when `nav_menus` component is excluded from loading. See [35304]. See #33327.

Props westonruter, DrewAPicture.
Fixes #33552.

Built from https://develop.svn.wordpress.org/trunk@35307


git-svn-id: http://core.svn.wordpress.org/trunk@35273 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/css/customize-controls-rtl.css

@@ -3,6 +3,18 @@ body {
 	-webkit-text-size-adjust: 100%;
 }
 
+button.not-a-button {
+	background: transparent;
+	border: none;
+	-webkit-box-shadow: none;
+	box-shadow: none;
+	-webkit-border-radius: 0;
+	border-radius: 0;
+	outline: 0;
+	padding: 0;
+	margin: 0;
+}
+
 #customize-controls a {
 	text-decoration: none;
 }

wp-admin/css/customize-controls.css

@@ -3,6 +3,18 @@ body {
 	-webkit-text-size-adjust: 100%;
 }
 
+button.not-a-button {
+	background: transparent;
+	border: none;
+	-webkit-box-shadow: none;
+	box-shadow: none;
+	-webkit-border-radius: 0;
+	border-radius: 0;
+	outline: 0;
+	padding: 0;
+	margin: 0;
+}
+
 #customize-controls a {
 	text-decoration: none;
 }

wp-admin/css/customize-nav-menus-rtl.css

@@ -612,18 +612,6 @@
 	background: transparent;
 }
 
-button.not-a-button {
-	background: transparent;
-	border: none;
-	-webkit-box-shadow: none;
-	box-shadow: none;
-	-webkit-border-radius: 0;
-	border-radius: 0;
-	outline: 0;
-	padding: 0;
-	margin: 0;
-}
-
 #available-menu-items .accordion-section-title button {
 	display: block;
 	width: 28px;

wp-admin/css/customize-nav-menus.css

@@ -612,18 +612,6 @@
 	background: transparent;
 }
 
-button.not-a-button {
-	background: transparent;
-	border: none;
-	-webkit-box-shadow: none;
-	box-shadow: none;
-	-webkit-border-radius: 0;
-	border-radius: 0;
-	outline: 0;
-	padding: 0;
-	margin: 0;
-}
-
 #available-menu-items .accordion-section-title button {
 	display: block;
 	width: 28px;

wp-includes/class-wp-customize-manager.php

@@ -191,11 +191,32 @@ final class WP_Customize_Manager {
 		require_once( ABSPATH . WPINC . '/class-wp-customize-panel.php' );
 		require_once( ABSPATH . WPINC . '/class-wp-customize-section.php' );
 		require_once( ABSPATH . WPINC . '/class-wp-customize-control.php' );
-		require_once( ABSPATH . WPINC . '/class-wp-customize-widgets.php' );
-		require_once( ABSPATH . WPINC . '/class-wp-customize-nav-menus.php' );
 
-		$this->widgets = new WP_Customize_Widgets( $this );
-		$this->nav_menus = new WP_Customize_Nav_Menus( $this );
+		/**
+		 * Filter the core Customizer components to load.
+		 *
+		 * This allows Core components to be excluded from being instantiated by
+		 * filtering them out of the array. Note that this filter generally runs
+		 * during the <code>plugins_loaded</code> action, so it cannot be added
+		 * in a theme.
+		 *
+		 * @since 4.4.0
+		 *
+		 * @see WP_Customize_Manager::__construct()
+		 *
+		 * @param array                $components List of core components to load.
+		 * @param WP_Customize_Manager $this       WP_Customize_Manager instance.
+		 */
+		$components = apply_filters( 'customize_loaded_components', array( 'widgets', 'nav_menus' ), $this );
+
+		if ( in_array( 'widgets', $components ) ) {
+			require_once( ABSPATH . WPINC . '/class-wp-customize-widgets.php' );
+			$this->widgets = new WP_Customize_Widgets( $this );
+		}
+		if ( in_array( 'nav_menus', $components ) ) {
+			require_once( ABSPATH . WPINC . '/class-wp-customize-nav-menus.php' );
+			$this->nav_menus = new WP_Customize_Nav_Menus( $this );
+		}
 
 		add_filter( 'wp_die_handler', array( $this, 'wp_die_handler' ) );
 

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-35306';
+$wp_version = '4.4-alpha-35307';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.