Make the DatabaseTracker thread-safe.

WebCore/storage/OriginQuotaManager.h

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 27 matching lines @@
 
 namespace WebCore {
 
 class Database;
 class OriginUsageRecord;
 
 class OriginQuotaManager : public Noncopyable {
 public:
     OriginQuotaManager();
 
+    bool tryLock();
     void lock();
     void unlock();
 
     void trackOrigin(PassRefPtr<SecurityOrigin>);
     bool tracksOrigin(SecurityOrigin*) const;
     void addDatabase(SecurityOrigin*, const String& databaseIdentifier, const String& fullPath);
     void removeDatabase(SecurityOrigin*, const String& databaseIdentifier);
     void removeOrigin(SecurityOrigin*);
 
     void markDatabase(Database*); // Mark dirtiness of a specific database.
     unsigned long long diskUsage(SecurityOrigin*) const;
 
 private:
     mutable Mutex m_usageRecordGuard;
 #ifndef NDEBUG
     bool m_usageRecordGuardLocked;
 #endif
 
     typedef HashMap<RefPtr<SecurityOrigin>, OriginUsageRecord*, SecurityOriginHash> OriginUsageMap;
     OriginUsageMap m_usageMap;
 };
 
 } // namespace WebCore
 
 #endif // ENABLE(DATABASE)
 
 #endif // OriginQuotaManager_h