WordPress/wp-admin/includes/class-plugin-upgrader-skin.php

<?php
/**
 * Upgrader API: Plugin_Upgrader_Skin class
 *
 * @package WordPress
 * @subpackage Upgrader
 * @since 4.6.0
 */

/**
 * Plugin Upgrader Skin for WordPress Plugin Upgrades.
 *
 * @since 2.8.0
 */
class Plugin_Upgrader_Skin extends WP_Upgrader_Skin {
	public $plugin = '';
	public $plugin_active = false;
	public $plugin_network_active = false;

	/**
	 *
	 * @param array $args
	 */
	public function __construct( $args = array() ) {
		$defaults = array( 'url' => '', 'plugin' => '', 'nonce' => '', 'title' => __('Update Plugin') );
		$args = wp_parse_args($args, $defaults);

		$this->plugin = $args['plugin'];

		$this->plugin_active = is_plugin_active( $this->plugin );
		$this->plugin_network_active = is_plugin_active_for_network( $this->plugin );

		parent::__construct($args);
	}

	/**
	 * @access public
	 */
	public function after() {
		$this->plugin = $this->upgrader->plugin_info();
		if ( !empty($this->plugin) && !is_wp_error($this->result) && $this->plugin_active ){
			// Currently used only when JS is off for a single plugin update?
			echo '<iframe title="' . esc_attr__( 'Update progress' ) . '" style="border:0;overflow:hidden" width="100%" height="170" src="' . wp_nonce_url( 'update.php?action=activate-plugin&networkwide=' . $this->plugin_network_active . '&plugin=' . urlencode( $this->plugin ), 'activate-plugin_' . $this->plugin ) . '"></iframe>';
		}

		$this->decrement_update_count( 'plugin' );

		$update_actions =  array(
			'activate_plugin' => '<a href="' . wp_nonce_url( 'plugins.php?action=activate&amp;plugin=' . urlencode( $this->plugin ), 'activate-plugin_' . $this->plugin) . '" target="_parent">' . __( 'Activate Plugin' ) . '</a>',
			'plugins_page' => '<a href="' . self_admin_url( 'plugins.php' ) . '" target="_parent">' . __( 'Return to Plugins page' ) . '</a>'
		);
		if ( $this->plugin_active || ! $this->result || is_wp_error( $this->result ) || ! current_user_can( 'activate_plugins' ) )
			unset( $update_actions['activate_plugin'] );

		/**
		 * Filter the list of action links available following a single plugin update.
		 *
		 * @since 2.7.0
		 *
		 * @param array  $update_actions Array of plugin action links.
		 * @param string $plugin         Path to the plugin file.
		 */
		$update_actions = apply_filters( 'update_plugin_complete_actions', $update_actions, $this->plugin );

		if ( ! empty($update_actions) )
			$this->feedback(implode(' | ', (array)$update_actions));
	}
}