Check if the parserthread has been shut down before returning it to the ThreadedDataProvider

Source/core/html/parser/HTMLDocumentParser.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:
  * 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 67 matching lines @@
 class ParserDataReceiver : public blink::WebThreadedDataReceiver {
 public:
     explicit ParserDataReceiver(WeakPtr<BackgroundHTMLParser> backgroundParser)
         : m_backgroundParser(backgroundParser)
     {
     }
 
     // WebThreadedDataReceiver
     virtual void acceptData(const char* data, int dataLength) OVERRIDE FINAL
     {
-        ASSERT(backgroundThread()->isCurrentThread());
+        ASSERT(backgroundThread() && backgroundThread()->isCurrentThread());
         if (m_backgroundParser.get())
             m_backgroundParser.get()->appendRawBytesFromParserThread(data, dataLength);
     }
 
     virtual blink::WebThread* backgroundThread() OVERRIDE FINAL
     {
-        return &HTMLParserThread::shared()->platformThread();
+        if (HTMLParserThread::shared())
+            return &HTMLParserThread::shared()->platformThread();
+
+        return 0;
     }
 
 private:
     WeakPtr<BackgroundHTMLParser> m_backgroundParser;
 };
 
 HTMLDocumentParser::HTMLDocumentParser(HTMLDocument& document, bool reportErrors)
     : ScriptableDocumentParser(document)
     , m_options(&document)
     , m_token(m_options.useThreading ? nullptr : adoptPtr(new HTMLToken))
@@ skipping 950 matching lines @@
 void HTMLDocumentParser::setDecoder(PassOwnPtr<TextResourceDecoder> decoder)
 {
     ASSERT(decoder);
     DecodedDataDocumentParser::setDecoder(decoder);
 
     if (m_haveBackgroundParser)
         HTMLParserThread::shared()->postTask(bind(&BackgroundHTMLParser::setDecoder, m_backgroundParser, takeDecoder()));
 }
 
 }