Use AtomicString type more consistently for mimeType / encoding

Source/core/loader/TextResourceDecoderBuilder.cpp

 /*
  * Copyright (C) 2013 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 26 matching lines @@
 #include "platform/weborigin/SecurityOrigin.h"
 
 namespace WebCore {
 
 static inline bool canReferToParentFrameEncoding(const Frame* frame, const Frame* parentFrame)
 {
     return parentFrame && parentFrame->document()->securityOrigin()->canAccess(frame->document()->securityOrigin());
 }
 
 
-TextResourceDecoderBuilder::TextResourceDecoderBuilder(const String& mimeType, const String& encoding, bool encodingUserChoosen)
+TextResourceDecoderBuilder::TextResourceDecoderBuilder(const AtomicString& mimeType, const AtomicString& encoding, bool encodingUserChoosen)
     : m_mimeType(mimeType)
     , m_encoding(encoding)
     , m_encodingWasChosenByUser(encodingUserChoosen)
 {
 }
 
 TextResourceDecoderBuilder::~TextResourceDecoderBuilder()
 {
 }
 
 
 inline PassOwnPtr<TextResourceDecoder> TextResourceDecoderBuilder::createDecoderInstance(Document* document)
 {
     if (Frame* frame = document->frame()) {
         if (Settings* settings = frame->settings())
             return TextResourceDecoder::create(m_mimeType, settings->defaultTextEncodingName(), settings->usesEncodingDetector());
     }
 
     return TextResourceDecoder::create(m_mimeType, String());
 }
 
 inline void TextResourceDecoderBuilder::setupEncoding(TextResourceDecoder* decoder, Document* document)
 {
     Frame* frame = document->frame();
     Frame* parentFrame = frame ? frame->tree().parent() : 0;
 
     if (!m_encoding.isEmpty())
-        decoder->setEncoding(m_encoding, m_encodingWasChosenByUser ? TextResourceDecoder::UserChosenEncoding : TextResourceDecoder::EncodingFromHTTPHeader);
+        decoder->setEncoding(m_encoding.string(), m_encodingWasChosenByUser ? TextResourceDecoder::UserChosenEncoding : TextResourceDecoder::EncodingFromHTTPHeader);
 
     // Set the hint encoding to the parent frame encoding only if
     // the parent and the current frames share the security origin.
     // We impose this condition because somebody can make a child frameg63
     // containing a carefully crafted html/javascript in one encoding
     // that can be mistaken for hintEncoding (or related encoding) by
     // an auto detector. When interpreted in the latter, it could be
     // an attack vector.
     // FIXME: This might be too cautious for non-7bit-encodings and
     // we may consider relaxing this later after testing.
     if (frame && canReferToParentFrameEncoding(frame, parentFrame)) {
         if (parentFrame->document()->encodingWasDetectedHeuristically())
             decoder->setHintEncoding(parentFrame->document()->encoding());
 
         if (m_encoding.isEmpty())
             decoder->setEncoding(parentFrame->document()->inputEncoding(), TextResourceDecoder::EncodingFromParentFrame);
     }
 }
 
 PassOwnPtr<TextResourceDecoder> TextResourceDecoderBuilder::buildFor(Document* document)
 {
     OwnPtr<TextResourceDecoder> decoder = createDecoderInstance(document);
     setupEncoding(decoder.get(), document);
     return decoder.release();
 }
 
 void TextResourceDecoderBuilder::clear()
 {
     if (!m_encodingWasChosenByUser)
-        m_encoding = String();
+        m_encoding = nullAtom;
 }
 
 }