Restore sessionStorage when chrome restarts.

content/browser/in_process_webkit/dom_storage_context.h

Index: content/browser/in_process_webkit/dom_storage_context.h
diff --git a/content/browser/in_process_webkit/dom_storage_context.h b/content/browser/in_process_webkit/dom_storage_context.h
index 05e404043933470b3198d1cf25b8686e51421ea8..0309679e7d07011dd8241a9dd688cf5036695f0d 100644
--- a/content/browser/in_process_webkit/dom_storage_context.h
+++ b/content/browser/in_process_webkit/dom_storage_context.h
@@ -67,6 +67,12 @@ class CONTENT_EXPORT DOMStorageContext {
   // namespace if it hasn't been already.
   DOMStorageNamespace* GetStorageNamespace(int64 id, bool allocation_allowed);
 
+  // Creates a session storage namespace which is backed up by the existing
+  // |session_storage_directory|.
+  DOMStorageNamespace* RecreateSessionStorageNamespace(
+      int64 id,
+      const FilePath& session_storage_directory);
+
   // Sometimes an event from one DOM storage message filter requires
   // communication to all of them.
   typedef std::set<DOMStorageMessageFilter*> MessageFilterSet;
@@ -94,6 +100,9 @@ class CONTENT_EXPORT DOMStorageContext {
   // The local storage directory.
   static const FilePath::CharType kLocalStorageDirectory[];
 
+  // The session storage directory.
+  static const FilePath::CharType kSessionStorageDirectory[];
+
   // The local storage file extension.
   static const FilePath::CharType kLocalStorageExtension[];
 
@@ -113,6 +122,10 @@ class CONTENT_EXPORT DOMStorageContext {
     data_path_ = data_path;
   }
 
+  // Deletes the session storages which are not in |needed_session_storages|.
+  void DeleteUnneededSessionStorages(
+      const std::set<std::string>& needed_session_storages);
+
  private:
 
   FRIEND_TEST_ALL_PREFIXES(DOMStorageTest, SessionOnly);
@@ -132,7 +145,8 @@ class CONTENT_EXPORT DOMStorageContext {
   // That said, we know this is safe because this class is destroyed on the
   // WebKit thread, so there's no way it could be destroyed before this is run.
   static void CompleteCloningSessionStorage(DOMStorageContext* context,
-                                            int64 existing_id, int64 clone_id);
+                                            int64 existing_id, int64 clone_id,
+                                            const FilePath& data_path);
 
   // The last used storage_area_id and storage_namespace_id's.  For the storage
   // namespaces, IDs allocated on the UI thread are positive and count up while