Web SQL: Make sure DatabaseManager is used only in the main thread.

Source/modules/webdatabase/AbstractDatabaseServer.h

 /*
  * 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 28 matching lines @@
 class DatabaseManagerClient;
 class SecurityOrigin;
 
 class AbstractDatabaseServer {
 public:
     virtual String fullPathForDatabase(SecurityOrigin*, const String& name, bool createIfDoesNotExist = true) = 0;
     virtual PassRefPtrWillBeRawPtr<DatabaseBackendBase> openDatabase(DatabaseContext*,
         const String& name, const String& expectedVersion, const String& displayName, unsigned long estimatedSize,
         bool setVersionInNewDatabase, DatabaseError&, String& errorMessage) = 0;
 
-    virtual void closeDatabasesImmediately(const String& originIdentifier, const String& name) = 0;
-
 protected:
     AbstractDatabaseServer() { }
     virtual ~AbstractDatabaseServer() { }
 };
 
 } // namespace blink
 
 #endif // AbstractDatabaseServer_h