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

webkit/dom_storage/dom_storage_namespace.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/dom_storage/dom_storage_namespace.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 99 matching lines @@
     area->DeleteOrigin();
   }
 }
 
 void DomStorageNamespace::DeleteSessionStorageOrigin(const GURL& origin) {
   DomStorageArea* area = OpenStorageArea(origin);
   area->FastClear();
   CloseStorageArea(area);
 }
 
-void DomStorageNamespace::PurgeMemory() {
+void DomStorageNamespace::PurgeMemory(PurgeOption option) {
   if (directory_.empty())
     return;  // We can't purge w/o backing on disk.
   AreaMap::iterator it = areas_.begin();
   while (it != areas_.end()) {
     // Leave it alone if changes are pending
     if (it->second.area_->HasUncommittedChanges()) {
       ++it;
       continue;
     }
 
     // If not in use, we can shut it down and remove
     // it from our collection entirely.
     if (it->second.open_count_ == 0) {
       it->second.area_->Shutdown();
       areas_.erase(it++);
       continue;
     }
 
-    // Otherwise, we can clear caches and such.
-    it->second.area_->PurgeMemory();
+    if (option == PURGE_AGGRESSIVE) {
+      // If aggressive is true, we clear caches and such
+      // for opened areas.
+      it->second.area_->PurgeMemory();
+    }
+
     ++it;
   }
 }
 
 void DomStorageNamespace::Shutdown() {
   AreaMap::const_iterator it = areas_.begin();
   for (; it != areas_.end(); ++it)
     it->second.area_->Shutdown();
 }
 
+unsigned int DomStorageNamespace::CountInMemoryAreas() const {
+  unsigned int area_count = 0;
+  for (AreaMap::const_iterator it = areas_.begin(); it != areas_.end(); ++it) {
+    if (it->second.area_->IsLoadedInMemory())
+      ++area_count;
+  }
+  return area_count;
+}
 
 DomStorageNamespace::AreaHolder*
 DomStorageNamespace::GetAreaHolder(const GURL& origin) {
   AreaMap::iterator found = areas_.find(origin);
   if (found == areas_.end())
     return NULL;
   return &(found->second);
 }
 
 // AreaHolder
 
 DomStorageNamespace::AreaHolder::AreaHolder()
     : open_count_(0) {
 }
 
 DomStorageNamespace::AreaHolder::AreaHolder(
     DomStorageArea* area, int count)
     : area_(area), open_count_(count) {
 }
 
 DomStorageNamespace::AreaHolder::~AreaHolder() {
 }
 
 }  // namespace dom_storage