includes/class-fs-plugin-updater.php
protected function try_activate_plugin( $file_path ) {
            $activate = activate_plugin( $file_path, '', $this->_fs->is_network_active() );

            return is_wp_error( $activate ) ?
                $activate :
                true;
        }
protected function try_activate_plugin( $file_path ) {
            $activate = activate_plugin( $file_path, '', $this->_fs->is_network_active() );

            return is_wp_error( $activate ) ?
                $activate :
                true;
        }
protected function try_activate_plugin ( $ file_path ) { $ activate = activate_plugin ( $ file_path , '' , $ this -> _fs -> is_network_active ( ) ) ; return is_wp_error ( $ activate ) ? $ activate : true ; }
Tries to activate a plugin. If fails, returns the error.

@author Vova Feldman
@since  1.2.1.7

@param string $file_path Path within wp-plugins/ to main plugin file.
This determines the styling of the output messages.

@return bool|WP_Error
Tries to activate a plugin . If fails returns the error .