Persist sessionStorage on disk.

chrome/browser/sessions/session_service.h

Index: chrome/browser/sessions/session_service.h
diff --git a/chrome/browser/sessions/session_service.h b/chrome/browser/sessions/session_service.h
index f2f4cc16abfbe0f97fa54efd3de6cc594aabb6bf..18a8a2bbba158923ca432728a211979e3263718c 100644
--- a/chrome/browser/sessions/session_service.h
+++ b/chrome/browser/sessions/session_service.h
@@ -255,6 +255,9 @@ class SessionService : public BaseSessionService,
   SessionCommand* CreatePinnedStateCommand(const SessionID& tab_id,
                                            bool is_pinned);
 
+  void CreateAndScheduleSessionStorageAssociatedCommand(int64 id,
+                                                        int64 real_id);
+
   // Callback from the backend for getting the commands from the save file.
   // Converts the commands in SessionWindows and notifies the real callback.
   void OnGotSessionCommands(
@@ -473,6 +476,12 @@ class SessionService : public BaseSessionService,
   // without quitting.
   bool force_browser_not_alive_with_no_windows_;
 
+  // Map from session storage namespace id (stored by |SessionStorageNamespace|)
+  // to a pair (window_id, tab_id).
+  typedef std::map<int64,
+                   std::pair<SessionID, SessionID> > SessionStorageIdToTab;
+  SessionStorageIdToTab session_storage_id_to_tab_;
+
   DISALLOW_COPY_AND_ASSIGN(SessionService);
 };