Refactor MIME type related methods in XHR for readability

Source/core/xml/XMLHttpRequest.h

Index: Source/core/xml/XMLHttpRequest.h
diff --git a/Source/core/xml/XMLHttpRequest.h b/Source/core/xml/XMLHttpRequest.h
index d2060c8c27ee07eae3983a779c186437975e60f5..0a5a3e9e04223da42465d1a74d24bc4d029d1ece 100644
--- a/Source/core/xml/XMLHttpRequest.h
+++ b/Source/core/xml/XMLHttpRequest.h
@@ -160,7 +160,18 @@ private:
     virtual void didFail(const ResourceError&) OVERRIDE;
     virtual void didFailRedirectCheck() OVERRIDE;
 
-    AtomicString responseMIMEType() const;
+    // Returns the MIME type part of m_mimeTypeOverride if present and
+    // successfully parsed, or returns one of the "Content-Type" header value
+    // of the received response.
+    //
+    // This method is named after the term "final MIME type" defined in the
+    // spec but doesn't convert the result to ASCII lowercase as specified in
+    // the spec. Must be lowered later or compared using case insensitive
+    // comparison functions if required.
+    AtomicString finalMIMEType() const;

[sof, 2014/08/11 12:19:38]

The term "final MIME type" is a relatively obscure spec-internal name and
doesn't impart much to the general reader; can't we do better?
finalResponseMIMEType() ?

[tyoshino (SeeGerritForStatus), 2014/08/11 13:10:46]

OK. Fixed

+    // The same as finalMIMEType() but fallbacks to "text/xml" if
+    // finalMIMEType() returns an empty string.
+    AtomicString finalMIMETypeWithFallback() const;
     bool responseIsXML() const;
 
     PassOwnPtr<TextResourceDecoder> createDecoder() const;
@@ -212,6 +223,8 @@ private:
     KURL m_url;
     AtomicString m_method;
     HTTPHeaderMap m_requestHeaders;
+    // Not converted to ASCII lowercase. Must be lowered later or compared
+    // using case insensitive comparison functions if needed.
     AtomicString m_mimeTypeOverride;
     unsigned long m_timeoutMilliseconds;
     RefPtrWillBeMember<Blob> m_responseBlob;
@@ -221,7 +234,7 @@ private:
     State m_state;
 
     ResourceResponse m_response;
-    String m_responseEncoding;
+    String m_finalCharset;

[sof, 2014/08/11 12:19:38]

Same comment re: name -- m_finalResponseCharset?

[tyoshino (SeeGerritForStatus), 2014/08/11 13:10:46]

Done

 
     OwnPtr<TextResourceDecoder> m_decoder;