Refactoring: Simplify DocumentWriter by reorganizing its lifetime.

Source/core/loader/DocumentWriter.h

Index: Source/core/loader/DocumentWriter.h
diff --git a/Source/core/loader/DocumentWriter.h b/Source/core/loader/DocumentWriter.h
index 56c8aabd74ebe92c5c721b87e4a9ea6a80a6aa30..b7927ef780e1eeda87f192e2db4e0d5893105e3a 100644
--- a/Source/core/loader/DocumentWriter.h
+++ b/Source/core/loader/DocumentWriter.h
@@ -44,46 +44,38 @@ class TextResourceDecoder;
 class DocumentWriter {
     WTF_MAKE_NONCOPYABLE(DocumentWriter);
 public:
-    explicit DocumentWriter(Frame*);
+    static PassOwnPtr<DocumentWriter> create(Document*, const String& mimeType = "", const String& encoding = "", bool encodingUserChoosen = false);
+
+    ~DocumentWriter();
+
+    void end();
 
     // This is only called by ScriptController::executeScriptIfJavaScriptURL
     // and always contains the result of evaluating a javascript: url.
     void replaceDocument(const String&, Document* ownerDocument);
 
-    void begin();
-    void begin(const KURL&, bool dispatchWindowObjectAvailable = true, Document* ownerDocument = 0);
     void addData(const char* bytes, size_t length);
-    void end();
     
-    void setFrame(Frame* frame) { m_frame = frame; }
-
     const String& mimeType() const { return m_decoderBuilder.mimeType(); }
-    void setMIMEType(const String& type) { m_decoderBuilder.setMIMEType(type); }
-    void setEncoding(const String& encoding, bool userChosen) { m_decoderBuilder.setEncoding(encoding, userChosen); }
 
     // Exposed for DocumentParser::appendBytes.
     void reportDataReceived();
+    // Exposed for DocumentLoader::replaceDocument.
+    void appendReplacingData(const String&);
 
     void setDocumentWasLoadedAsPartOfNavigation();
 
 private:
-    PassRefPtr<Document> createDocument(const KURL&);
-    void clear();
+    DocumentWriter(Document*, const String& mimeType, const String& encoding, bool encodingUserChoosen);
 
-    Frame* m_frame;
+    PassRefPtr<Document> createDocument(const KURL&);
 
+    Document* m_document;
     bool m_hasReceivedSomeData;
     TextResourceDecoderBuilder m_decoderBuilder;
 
     RefPtr<TextResourceDecoder> m_decoder;
     RefPtr<DocumentParser> m_parser;
-
-    enum WriterState {
-        NotStartedWritingState,
-        StartedWritingState,
-        FinishedWritingState,
-    };
-    WriterState m_state;
 };
 
 } // namespace WebCore