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\\edit\\Annotation' => $namespaces['Drupal\\edit'],
  );
  $this->discovery = new AnnotatedClassDiscovery('InPlaceEditor', $namespaces, $annotation_namespaces, 'Drupal\\edit\\Annotation\\InPlaceEditor');
  $this->discovery = new AlterDecorator($this->discovery, 'edit_editor');
  $this->discovery = new CacheDecorator($this->discovery, 'edit:editor');
  $this->factory = new DefaultFactory($this->discovery);
}