Overrides \Drupal\Component\Plugin\PluginManagerBase::__construct().
\Traversable $namespaces: An object that implements \Traversable which contains the root paths keyed by the corresponding namespace to look for plugin implementations,
public function __construct(\Traversable $namespaces) {
$annotation_namespaces = array(
'Drupal\\tour\\Annotation' => $namespaces['Drupal\\tour'],
);
$this->discovery = new AnnotatedClassDiscovery('tour/tip', $namespaces, $annotation_namespaces, 'Drupal\\tour\\Annotation\\Tip');
$this->discovery = new AlterDecorator($this->discovery, 'tour_tips_info');
$this->discovery = new CacheDecorator($this->discovery, 'tour');
$this->factory = new DefaultFactory($this->discovery);
}