Make the DatabaseTracker thread-safe.

WebCore/storage/OriginQuotaManager.cpp

 /*
  * 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 24 matching lines @@
 
 namespace WebCore {
 
 OriginQuotaManager::OriginQuotaManager()
 #ifndef NDEBUG
     : m_usageRecordGuardLocked(false)
 #endif
 {
 }
 
+bool OriginQuotaManager::tryLock()
+{
+    bool locked = m_usageRecordGuard.tryLock();
+#ifndef NDEBUG
+    if (locked)
+        m_usageRecordGuardLocked = true;
+    else
+        ASSERT(m_usageRecordGuardLocked);
+#endif
+    return locked;
+}
+
 void OriginQuotaManager::lock()
 {
     m_usageRecordGuard.lock();
 #ifndef NDEBUG
     m_usageRecordGuardLocked = true;
 #endif
 }
 
 void OriginQuotaManager::unlock()
 {
@@ skipping 61 matching lines @@
 
     OriginUsageRecord* usageRecord = m_usageMap.get(origin);
     ASSERT(usageRecord);
 
     return usageRecord->diskUsage();
 }
 
 }
 
 #endif // ENABLE(DATABASE)