Source

File: wp-admin/includes/class-wp-plugin-install-list-table.php

protected function get_installed_plugins() {
		$plugins = array();

		$plugin_info = get_site_transient( 'update_plugins' );
		if ( isset( $plugin_info->no_update ) ) {
			foreach ( $plugin_info->no_update as $plugin ) {
				$plugin->upgrade          = false;
				$plugins[ $plugin->slug ] = $plugin;
			}
		}

		if ( isset( $plugin_info->response ) ) {
			foreach ( $plugin_info->response as $plugin ) {
				$plugin->upgrade          = true;
				$plugins[ $plugin->slug ] = $plugin;
			}
		}

		return $plugins;
	}