Revert of Revert "Moved text decoding to the parser thread"

Source/core/dom/DecodedDataDocumentParser.h

Index: Source/core/dom/DecodedDataDocumentParser.h
diff --git a/Source/core/dom/DecodedDataDocumentParser.h b/Source/core/dom/DecodedDataDocumentParser.h
index b05810960f7de860b9792acd59abce049f66ccfb..6264bbbf59b10d129c53b3313d3fd1a2945ae4a6 100644
--- a/Source/core/dom/DecodedDataDocumentParser.h
+++ b/Source/core/dom/DecodedDataDocumentParser.h
@@ -42,10 +42,11 @@ public:
     // The below functions are used by DocumentWriter (the loader).
     virtual void appendBytes(const char* bytes, size_t length) OVERRIDE;
     virtual void flush() OVERRIDE;
-    virtual bool needsDecoder() const OVERRIDE FINAL { return !m_decoder; }
-    virtual void setDecoder(PassOwnPtr<TextResourceDecoder>) OVERRIDE FINAL;
+    virtual bool needsDecoder() const OVERRIDE FINAL { return m_needsDecoder; }
+    virtual void setDecoder(PassOwnPtr<TextResourceDecoder>) OVERRIDE;
     virtual TextResourceDecoder* decoder() OVERRIDE FINAL;
-    virtual void setHasAppendedData() OVERRIDE FINAL;
+
+    PassOwnPtr<TextResourceDecoder> takeDecoder();
 
 protected:
     explicit DecodedDataDocumentParser(Document*);
@@ -57,7 +58,7 @@ private:
 
     void updateDocument(String& decodedData);
 
-    bool m_hasAppendedData;
+    bool m_needsDecoder;
     OwnPtr<TextResourceDecoder> m_decoder;
 };