Remove ActiveDOMObject::willStop, and introduce WorkerGlobalScope::TerminationObserver.

Source/modules/webdatabase/DatabaseContext.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 Google, 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 87 matching lines @@
     : ActiveDOMObject(context)
     , m_hasOpenDatabases(false)
     , m_hasRequestedTermination(false)
 {
     // ActiveDOMObject expects this to be called to set internal flags.
     suspendIfNeeded();
 
     // For debug accounting only. We must do this before we register the
     // instance. The assertions assume this.
     DatabaseManager::manager().didConstructDatabaseContext();
+    if (context->isWorkerGlobalScope())
+        toWorkerGlobalScope(context)->registerTerminationObserver(this);
 }
 
 DatabaseContext::~DatabaseContext()
 {
     // For debug accounting only. We must call this last. The assertions assume
     // this.
     DatabaseManager::manager().didDestructDatabaseContext();
 }
 
 void DatabaseContext::trace(Visitor* visitor)
 {
     visitor->trace(m_databaseThread);
     visitor->trace(m_openSyncDatabases);
 }
 
 // This is called if the associated ExecutionContext is destructing while
 // we're still associated with it. That's our cue to disassociate and shutdown.
 // To do this, we stop the database and let everything shutdown naturally
 // because the database closing process may still make use of this context.
 // It is not safe to just delete the context here.
 void DatabaseContext::contextDestroyed()
 {
     RefPtrWillBeRawPtr<DatabaseContext> protector(this);
     stopDatabases();
+    if (executionContext()->isWorkerGlobalScope())

[sof, 2014/04/23 09:04:26]

Clarifying question: is this access of the WorkerGlobalScope safe in the Oilpan
case?

[tkent, 2014/04/23 09:13:35]

Yes, it's safe.

+        toWorkerGlobalScope(executionContext())->unregisterTerminationObserver(this);
     DatabaseManager::manager().unregisterDatabaseContext(this);
     ActiveDOMObject::contextDestroyed();
 }
 
-void DatabaseContext::willStop()
+void DatabaseContext::wasRequestedToTerminate()
 {
     DatabaseManager::manager().interruptAllDatabasesForContext(this);
 }
 
 // stop() is from stopActiveDOMObjects() which indicates that the owner LocalFrame
 // or WorkerThread is shutting down. Initiate the orderly shutdown by stopping
 // the associated databases.
 void DatabaseContext::stop()
 {
     stopDatabases();
@@ skipping 107 matching lines @@
 {
     return executionContext()->securityOrigin();
 }
 
 bool DatabaseContext::isContextThread() const
 {
     return executionContext()->isContextThread();
 }
 
 } // namespace WebCore