merged branch endroid/master (PR #8488)

This PR was squashed before being merged into the master branch (closes #8488).

Discussion
----------

Add container aware trait

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | will create one if merged

This trait can be used inside a class to make it container aware. As it is not always possible to extend the abstract ContainerAware class, the code for creating a container aware class is usually copied over and over (most of the time unchanged), resulting in a lot of redundant code in your project. As my projects are PHP 5.4 based nowadays, I would like to be able to use a trait in these scenarios to improve my workflow.

Commits
-------

4c9e606 Add container aware trait

src/Symfony/Component/DependencyInjection/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+2.4.0
+-----
+
+ * added ContainerAwareTrait to add default container aware behavior to a class
+
 2.2.0
 -----
 

src/Symfony/Component/DependencyInjection/ContainerAwareTrait.php

@@ -0,0 +1,35 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DependencyInjection;
+
+/**
+ * ContainerAware trait.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+trait ContainerAwareTrait
+{
+    /**
+     * @var ContainerInterface
+     */
+    protected $container;
+
+    /**
+     * Sets the Container associated with this Controller.
+     *
+     * @param ContainerInterface $container A ContainerInterface instance
+     */
+    public function setContainer(ContainerInterface $container = null)
+    {
+        $this->container = $container;
+    }
+}