Add changelog for deprecated DbalSessionHandler

UPGRADE-3.4.md

@@ -63,6 +63,13 @@ Debug
 
  * Support for stacked errors in the `ErrorHandler` is deprecated and will be removed in Symfony 4.0.
 
+DoctrineBridge
+--------------
+
+* Deprecated `Symfony\Bridge\Doctrine\HttpFoundation\DbalSessionHandler` and
+  `Symfony\Bridge\Doctrine\HttpFoundation\DbalSessionHandlerSchema`. Use
+  `Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler` instead.
+
 EventDispatcher
 ---------------
 

UPGRADE-4.0.md

@@ -186,6 +186,13 @@ DependencyInjection
 
  * The `ExtensionCompilerPass` has been moved to before-optimization passes with priority -1000.
 
+DoctrineBridge
+--------------
+
+* The `Symfony\Bridge\Doctrine\HttpFoundation\DbalSessionHandler` and
+  `Symfony\Bridge\Doctrine\HttpFoundation\DbalSessionHandlerSchema` have been removed. Use
+  `Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler` instead.
+
 EventDispatcher
 ---------------
 

src/Symfony/Bridge/Doctrine/CHANGELOG.md

@@ -6,6 +6,8 @@ CHANGELOG
 
  * added support for doctrine/dbal v2.6 types
  * added cause of UniqueEntity constraint violation
+ * deprecated `DbalSessionHandler` and `DbalSessionHandlerSchema` in favor of
+   `Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler`
 
 3.1.0
 -----