[DI] Deprecate ContainerAware in favor of ContainerAwareTrait

src/Symfony/Component/DependencyInjection/CHANGELOG.md

@@ -4,6 +4,7 @@ CHANGELOG
 2.8.0
 -----
 
+ * deprecated the abstract ContainerAware class in favor of ContainerAwareTrait
  * deprecated IntrospectableContainerInterface, to be merged with ContainerInterface in 3.0
  * allowed specifying a directory to recursively load all configuration files it contains
  * deprecated the concept of scopes

src/Symfony/Component/DependencyInjection/ContainerAware.php

@@ -15,6 +15,8 @@ namespace Symfony\Component\DependencyInjection;
  * A simple implementation of ContainerAwareInterface.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since version 2.8, to be removed in 3.0. Use the ContainerAwareTrait instead.
  */
 abstract class ContainerAware implements ContainerAwareInterface
 {