[Extensions] Remove the "use_movable_types" entry from idl/json files

extensions/common/api/networking_private.idl

Index: extensions/common/api/networking_private.idl
diff --git a/extensions/common/api/networking_private.idl b/extensions/common/api/networking_private.idl
index 5088f0177949ebd900fde5939b8f3791b248e2dd..1df8ec7ace6dde39c2a61f6343fb82a716704d5e 100644
--- a/extensions/common/api/networking_private.idl
+++ b/extensions/common/api/networking_private.idl
@@ -27,7 +27,7 @@
 // TODO(stevenjb/pneubeck): Merge the ONC documentation with this document and
 // use it as the ONC specification.
 
-[use_movable_types=true] namespace networkingPrivate {
+namespace networkingPrivate {
   enum ActivationStateType {
     Activated, Activating, NotActivated, PartiallyActivated
   };