Move SessionStorageNamespace entirely into NavigationController and support StoragePartitions.

webkit/dom_storage/dom_storage_session.cc

Index: webkit/dom_storage/dom_storage_session.cc
diff --git a/webkit/dom_storage/dom_storage_session.cc b/webkit/dom_storage/dom_storage_session.cc
index f305a06c4e90e6663029c34916f7663a9f725649..57aedfa475e8ca1a39bb5b7c0c36a76c587f0582 100644
--- a/webkit/dom_storage/dom_storage_session.cc
+++ b/webkit/dom_storage/dom_storage_session.cc
@@ -40,6 +40,10 @@ void DomStorageSession::SetShouldPersist(bool should_persist) {
   should_persist_ = should_persist;
 }
 
+bool DomStorageSession::IsFromContext(DomStorageContext* context) {
+  return context_.get() == context;
+}
+
 DomStorageSession* DomStorageSession::Clone() {
   return CloneFrom(context_, namespace_id_);
 }