Persist sessionStorage on disk.

webkit/dom_storage/dom_storage_context.h

Index: webkit/dom_storage/dom_storage_context.h
diff --git a/webkit/dom_storage/dom_storage_context.h b/webkit/dom_storage/dom_storage_context.h
index b6fe5da6ba26b3925fc0f54da15c1f3721bd88cb..7e06cafc9e9c18f084e291b599c7d25ec2575b18 100644
--- a/webkit/dom_storage/dom_storage_context.h
+++ b/webkit/dom_storage/dom_storage_context.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <map>
+#include <set>
 #include <vector>
 
 #include "base/atomic_sequence_num.h"
@@ -35,6 +36,7 @@ class DomStorageArea;
 class DomStorageNamespace;
 class DomStorageSession;
 class DomStorageTaskRunner;
+class SessionStorageDatabase;
 
 // The Context is the root of an object containment hierachy for
 // Namespaces and Areas related to the owning profile.
@@ -160,6 +162,11 @@ class DomStorageContext
   void CloneSessionNamespace(int64 existing_id, int64 new_id,
                              const std::string& new_persistent_id);
 
+  // Deletes all namespaces which don't have an associated DomStorageNamespace
+  // alive. This function is used for deleting possible leftover data after an
+  // unclean exit. May be called on any thread.
+  void StartScavengingUnusedSessionStorage();
+
  private:
   friend class DomStorageContextTest;
   FRIEND_TEST_ALL_PREFIXES(DomStorageContextTest, Basics);
@@ -171,6 +178,9 @@ class DomStorageContext
 
   void ClearSessionOnlyOrigins();
 
+  void FindUnusedSessionStorageInCommitSequence();
+  void DeleteNextUnunsedNamespaceInCommitSequence();
+
   // Collection of namespaces keyed by id.
   StorageNamespaceMap namespaces_;
 
@@ -195,6 +205,14 @@ class DomStorageContext
   bool is_shutdown_;
   bool force_keep_session_state_;
   scoped_refptr<quota::SpecialStoragePolicy> special_storage_policy_;
+  scoped_refptr<SessionStorageDatabase> session_storage_database_;
+
+  // Persistent namespace IDs to protect from leftover data deletion (they will
+  // be needed for session restore).
+  std::set<std::string> protected_persistent_session_ids_;
+
+  // For cleaning up unused namespaces gradually.
+  std::vector<std::string> deletable_persistent_namespace_ids_;
 };
 
 }  // namespace dom_storage