merged branch drak/session_detect (PR #7571)

This PR was squashed before being merged into the master branch (closes #7571).

Discussion
----------

[2.3] Handle PHP sessions started outside of Symfony

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | symfony/symfony-docs#2474

This PR brings a way to allow Symfony2 to manage a session started outside of Symfony in such a way that quite explicit. It also introduces more robust detection of previously started sessions under PHP 5.3 and supports real session status detection under PHP 5.4

Commits
-------

df99902 [2.3] Handle PHP sessions started outside of Symfony

Author: fabpot

DependencyInjection/FrameworkExtension.php

@@ -318,6 +318,7 @@ private function registerSessionConfiguration(array $config, ContainerBuilder $c
         if (null == $config['handler_id']) {
             // Set the handler class to be null
             $container->getDefinition('session.storage.native')->replaceArgument(1, null);
+            $container->getDefinition('session.storage.php_bridge')->replaceArgument(1, null);
         } else {
             $container->setAlias('session.handler', $config['handler_id']);
         }
@@ -327,6 +328,7 @@ private function registerSessionConfiguration(array $config, ContainerBuilder $c
         $this->addClassesToCompile(array(
             'Symfony\\Bundle\\FrameworkBundle\\EventListener\\SessionListener',
             'Symfony\\Component\\HttpFoundation\\Session\\Storage\\NativeSessionStorage',
+            'Symfony\\Component\\HttpFoundation\\Session\\Storage\\PhpBridgeSessionStorage',
             'Symfony\\Component\\HttpFoundation\\Session\\Storage\\Handler\\NativeFileSessionHandler',
             'Symfony\\Component\\HttpFoundation\\Session\\Storage\\Proxy\\AbstractProxy',
             'Symfony\\Component\\HttpFoundation\\Session\\Storage\\Proxy\\SessionHandlerProxy',

Resources/config/session.xml

@@ -9,6 +9,7 @@
         <parameter key="session.flashbag.class">Symfony\Component\HttpFoundation\Session\Flash\FlashBag</parameter>
         <parameter key="session.attribute_bag.class">Symfony\Component\HttpFoundation\Session\Attribute\AttributeBag</parameter>
         <parameter key="session.storage.native.class">Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage</parameter>
+        <parameter key="session.storage.php_bridge.class">Symfony\Component\HttpFoundation\Session\Storage\PhpBridgeSessionStorage</parameter>
         <parameter key="session.storage.mock_file.class">Symfony\Component\HttpFoundation\Session\Storage\MockFileSessionStorage</parameter>
         <parameter key="session.handler.native_file.class">Symfony\Component\HttpFoundation\Session\Storage\Handler\NativeFileSessionHandler</parameter>
         <parameter key="session_listener.class">Symfony\Bundle\FrameworkBundle\EventListener\SessionListener</parameter>
@@ -26,6 +27,10 @@
             <argument type="service" id="session.handler" />
         </service>
 
+        <service id="session.storage.php_bridge" class="%session.storage.php_bridge.class%">
+            <argument type="service" id="session.handler" />
+        </service>
+
         <service id="session.flash_bag" class="%session.flashbag.class%" public="false" />
 
         <service id="session.attribute_bag" class="%session.attribute_bag.class%" public="false" />