Purge in-memory localStorage areas if the # of areas exceeds the limit

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 20ae0ed7fbf740a9dcc3339cfce2e2d498e2482c..b2f7332b8aaa628ebda723e303bc3645350744fd 100644
--- a/webkit/dom_storage/dom_storage_context.h
+++ b/webkit/dom_storage/dom_storage_context.h
@@ -33,6 +33,7 @@ class SpecialStoragePolicy;
 namespace dom_storage {
 
 class DomStorageArea;
+class DomStorageHost;
 class DomStorageNamespace;
 class DomStorageSession;
 class DomStorageTaskRunner;
@@ -167,6 +168,15 @@ class WEBKIT_STORAGE_EXPORT DomStorageContext
   // unclean exit.
   void StartScavengingUnusedSessionStorage();
 
+  // Performs a quick check to see if the given item (of |key| and |value|
+  // fits in the cache/storage.
+  // This may trigger aggressive memory purge if the in-memory cache is
+  // getting tight.
+  bool CanSetItem(DomStorageHost* host,
+                  int connection_id,
+                  const string16& key,
+                  const string16& value);
+
  private:
   friend class DomStorageContextTest;
   FRIEND_TEST_ALL_PREFIXES(DomStorageContextTest, Basics);
@@ -186,6 +196,13 @@ class WEBKIT_STORAGE_EXPORT DomStorageContext
   void DeleteNextUnusedNamespace();
   void DeleteNextUnusedNamespaceInCommitSequence();
 
+  // This forces the context to re-calculate the total area size next time
+  // GetInMemoryAreaSize() is called.
+  void InvalidateInMemoryAreaSize() {
+    total_area_size_ = -1;
+  }
+  int64 GetRemainingCacheSize();
+
   // Collection of namespaces keyed by id.
   StorageNamespaceMap namespaces_;
 
@@ -223,6 +240,9 @@ class WEBKIT_STORAGE_EXPORT DomStorageContext
   // Mapping between persistent namespace IDs and namespace IDs for
   // sessionStorage.
   std::map<std::string, int64> persistent_namespace_id_to_namespace_id_;
+
+  // Total in-memory map size.
+  int64 total_area_size_;
 };
 
 }  // namespace dom_storage