Create and store persistent unique ids for sessionStorage.

content/browser/dom_storage/session_storage_namespace_impl.cc

Index: content/browser/dom_storage/session_storage_namespace_impl.cc
diff --git a/content/browser/dom_storage/session_storage_namespace_impl.cc b/content/browser/dom_storage/session_storage_namespace_impl.cc
index fccc6f126adca88e05a4e71e91139b7f0e87af12..cc5848e65861c1b84433af5808605ece1f7d7b91 100644
--- a/content/browser/dom_storage/session_storage_namespace_impl.cc
+++ b/content/browser/dom_storage/session_storage_namespace_impl.cc
@@ -21,10 +21,19 @@ SessionStorageNamespaceImpl::SessionStorageNamespaceImpl(
                                             namepace_id_to_clone)) {
 }
 
+SessionStorageNamespaceImpl::SessionStorageNamespaceImpl(
+    DOMStorageContextImpl* context, const std::string& persistent_id)
+    : session_(new DomStorageSession(context->context(), persistent_id)) {
+}
+
 int64 SessionStorageNamespaceImpl::id() const {
   return session_->namespace_id();
 }
 
+const std::string& SessionStorageNamespaceImpl::persistent_id() const {
+  return session_->persistent_namespace_id();
+}
+
 SessionStorageNamespaceImpl* SessionStorageNamespaceImpl::Clone() {
   return new SessionStorageNamespaceImpl(session_->Clone());
 }