Virtual destructors should have virtual keyword.

webkit/quota/usage_tracker.h

 // Copyright (c) 2011 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.
 
 #ifndef WEBKIT_QUOTA_USAGE_TRACKER_H_
 #define WEBKIT_QUOTA_USAGE_TRACKER_H_
 #pragma once
 
 #include <list>
 #include <map>
@@ skipping 10 matching lines @@
 namespace quota {
 
 class ClientUsageTracker;
 
 // A helper class that gathers and tracks the amount of data stored in
 // all quota clients.
 // An instance of this class is created per storage type.
 class UsageTracker : public QuotaTaskObserver {
  public:
   UsageTracker(const QuotaClientList& clients, StorageType type);
-  ~UsageTracker();
+  virtual ~UsageTracker();
 
   StorageType type() const { return type_; }
   ClientUsageTracker* GetClientTracker(QuotaClient::ID client_id);
 
   void GetGlobalUsage(UsageCallback* callback);
   void GetHostUsage(const std::string& host, HostUsageCallback* callback);
   void UpdateUsageCache(QuotaClient::ID client_id,
                         const GURL& origin,
                         int64 delta);
 
@@ skipping 60 matching lines @@
   std::map<std::string, int64> host_usage_map_;
   std::map<std::string, GatherHostUsageTask*> host_usage_tasks_;
   HostUsageCallbackMap host_usage_callbacks_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientUsageTracker);
 };
 
 }  // namespace quota
 
 #endif  // WEBKIT_QUOTA_USAGE_TRACKER_H_