Remove manual ref()-deref() in DatabaseContext.

Source/modules/webdatabase/DatabaseManager.cpp

 /*
  * Copyright (C) 2012 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 50 matching lines @@
 DatabaseManager::DatabaseManager()
 #if !ASSERT_DISABLED
     : m_databaseContextRegisteredCount(0)
     , m_databaseContextInstanceCount(0)
 #endif
 {
     m_server = new DatabaseServer;
     ASSERT(m_server); // We should always have a server to work with.
 }
 
+DatabaseManager::~DatabaseManager()
+{
+}
+
 class DatabaseCreationCallbackTask FINAL : public ExecutionContextTask {
 public:
     static PassOwnPtr<DatabaseCreationCallbackTask> create(PassRefPtrWillBeRawPtr<Database> database, PassOwnPtr<DatabaseCallback> creationCallback)
     {
         return adoptPtr(new DatabaseCreationCallbackTask(database, creationCallback));
     }
 
     virtual void performTask(ExecutionContext*) OVERRIDE
     {
         m_creationCallback->handleEvent(m_database.get());
@@ skipping 19 matching lines @@
     ASSERT(m_databaseContextRegisteredCount <= m_databaseContextInstanceCount);
 
     return m_contextMap.get(context);
 }
 
 DatabaseContext* DatabaseManager::databaseContextFor(ExecutionContext* context)
 {
     if (DatabaseContext* databaseContext = existingDatabaseContextFor(context))
         return databaseContext;
     // We don't need to hold a reference returned by DatabaseContext::create
-    // because a DatabaseContext refers to itself internally. See
-    // DataabseContext::create.
+    // because DatabaseContext::create calls registerDatabaseContext, and the
+    // DatabaseManager holds a reference.
     return DatabaseContext::create(context).get();
 }
 
 void DatabaseManager::registerDatabaseContext(DatabaseContext* databaseContext)
 {
     MutexLocker locker(m_contextMapLock);
     ExecutionContext* context = databaseContext->executionContext();
     m_contextMap.set(context, databaseContext);
 #if !ASSERT_DISABLED
     m_databaseContextRegisteredCount++;
@@ skipping 144 matching lines @@
 {
     m_server->interruptAllDatabasesForContext(databaseContext->backend());
 }
 
 void DatabaseManager::logErrorMessage(ExecutionContext* context, const String& message)
 {
     context->addConsoleMessage(StorageMessageSource, ErrorMessageLevel, message);
 }
 
 } // namespace WebCore