protected function update( $value ) {
		if ( $this->is_updated ) {
			return;
		}

		$this->is_updated = true;
		$is_placeholder   = ( $this->post_id < 0 );
		$is_delete        = ( false === $value );

		// Update the cached value.
		$this->value = $value;

		add_filter( 'customize_save_response', array( $this, 'amend_customize_save_response' ) );

		if ( $is_delete ) {
			// If the current setting post is a placeholder, a delete request is a no-op.
			if ( $is_placeholder ) {
				$this->update_status = 'deleted';
			} else {
				$r = wp_delete_post( $this->post_id, true );

				if ( false === $r ) {
					$this->update_error  = new WP_Error( 'delete_failure' );
					$this->update_status = 'error';
				} else {
					$this->update_status = 'deleted';
				}
				// @todo send back the IDs for all associated nav menu items deleted, so these settings (and controls) can be removed from Customizer?
			}
		} else {

			// Handle saving menu items for menus that are being newly-created.
			if ( $value['nav_menu_term_id'] < 0 ) {
				$nav_menu_setting_id = sprintf( 'nav_menu[%s]', $value['nav_menu_term_id'] );
				$nav_menu_setting    = $this->manager->get_setting( $nav_menu_setting_id );

				if ( ! $nav_menu_setting || ! ( $nav_menu_setting instanceof WP_Customize_Nav_Menu_Setting ) ) {
					$this->update_status = 'error';
					$this->update_error  = new WP_Error( 'unexpected_nav_menu_setting' );
					return;
				}

				if ( false === $nav_menu_setting->save() ) {
					$this->update_status = 'error';
					$this->update_error  = new WP_Error( 'nav_menu_setting_failure' );
					return;
				}

				if ( $nav_menu_setting->previous_term_id !== intval( $value['nav_menu_term_id'] ) ) {
					$this->update_status = 'error';
					$this->update_error  = new WP_Error( 'unexpected_previous_term_id' );
					return;
				}

				$value['nav_menu_term_id'] = $nav_menu_setting->term_id;
			}

			// Handle saving a nav menu item that is a child of a nav menu item being newly-created.
			if ( $value['menu_item_parent'] < 0 ) {
				$parent_nav_menu_item_setting_id = sprintf( 'nav_menu_item[%s]', $value['menu_item_parent'] );
				$parent_nav_menu_item_setting    = $this->manager->get_setting( $parent_nav_menu_item_setting_id );

				if ( ! $parent_nav_menu_item_setting || ! ( $parent_nav_menu_item_setting instanceof WP_Customize_Nav_Menu_Item_Setting ) ) {
					$this->update_status = 'error';
					$this->update_error  = new WP_Error( 'unexpected_nav_menu_item_setting' );
					return;
				}

				if ( false === $parent_nav_menu_item_setting->save() ) {
					$this->update_status = 'error';
					$this->update_error  = new WP_Error( 'nav_menu_item_setting_failure' );
					return;
				}

				if ( $parent_nav_menu_item_setting->previous_post_id !== intval( $value['menu_item_parent'] ) ) {
					$this->update_status = 'error';
					$this->update_error  = new WP_Error( 'unexpected_previous_post_id' );
					return;
				}

				$value['menu_item_parent'] = $parent_nav_menu_item_setting->post_id;
			}

			// Insert or update menu.
			$menu_item_data = array(
				'menu-item-object-id'   => $value['object_id'],
				'menu-item-object'      => $value['object'],
				'menu-item-parent-id'   => $value['menu_item_parent'],
				'menu-item-position'    => $value['position'],
				'menu-item-type'        => $value['type'],
				'menu-item-title'       => $value['title'],
				'menu-item-url'         => $value['url'],
				'menu-item-description' => $value['description'],
				'menu-item-attr-title'  => $value['attr_title'],
				'menu-item-target'      => $value['target'],
				'menu-item-classes'     => $value['classes'],
				'menu-item-xfn'         => $value['xfn'],
				'menu-item-status'      => $value['status'],
			);

			$r = wp_update_nav_menu_item(
				$value['nav_menu_term_id'],
				$is_placeholder ? 0 : $this->post_id,
				wp_slash( $menu_item_data )
			);

			if ( is_wp_error( $r ) ) {
				$this->update_status = 'error';
				$this->update_error  = $r;
			} else {
				if ( $is_placeholder ) {
					$this->previous_post_id = $this->post_id;
					$this->post_id          = $r;
					$this->update_status    = 'inserted';
				} else {
					$this->update_status = 'updated';
				}
			}
		}

	}