Use toDocument instead of static_cast<Document*>.

Source/WebKit/chromium/src/DatabaseObserver.cpp

 /*
  * Copyright (C) 2010 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 115 matching lines @@
 
 }
 
 namespace WebCore {
 
 bool DatabaseObserver::canEstablishDatabase(ScriptExecutionContext* scriptExecutionContext, const String& name, const String& displayName, unsigned long estimatedSize)
 {
     ASSERT(scriptExecutionContext->isContextThread());
     ASSERT(scriptExecutionContext->isDocument() || scriptExecutionContext->isWorkerGlobalScope());
     if (scriptExecutionContext->isDocument()) {
-        Document* document = static_cast<Document*>(scriptExecutionContext);
+        Document* document = toDocument(scriptExecutionContext);
         WebFrameImpl* webFrame = WebFrameImpl::fromFrame(document->frame());
         if (!webFrame)
             return false;
         WebViewImpl* webView = webFrame->viewImpl();
         if (!webView)
             return false;
         if (webView->permissionClient())
             return webView->permissionClient()->allowDatabase(webFrame, name, displayName, estimatedSize);
     } else {
         WorkerGlobalScope* workerGlobalScope = static_cast<WorkerGlobalScope*>(scriptExecutionContext);
@@ skipping 49 matching lines @@
 {
     WebDatabase::observer()->reportExecuteStatementResult(WebDatabase(database), errorSite, webSqlErrorCode, sqliteErrorCode);
 }
 
 void DatabaseObserver::reportVacuumDatabaseResult(DatabaseBackendBase* database, int sqliteErrorCode)
 {
     WebDatabase::observer()->reportVacuumDatabaseResult(WebDatabase(database), sqliteErrorCode);
 }
 
 } // namespace WebCore