Add Accept-CH meta http-equiv support to the preloader.

Source/core/html/parser/HTMLPreloadScanner.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * 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
@@ skipping 99 matching lines @@
     CSSPreloadScanner m_cssScanner;
     const KURL m_documentURL;
     KURL m_predictedBaseElementURL;
     bool m_inStyle;
     bool m_inPicture;
     bool m_isAppCacheEnabled;
     bool m_isCSPEnabled;
     String m_pictureSourceURL;
     size_t m_templateCount;
     OwnPtr<CachedDocumentParameters> m_documentParameters;
+    ClientHintsPreferences m_clientHintsPreferences;
 
     Vector<Checkpoint> m_checkpoints;
 };
 
 class CORE_EXPORT HTMLPreloadScanner {
     WTF_MAKE_NONCOPYABLE(HTMLPreloadScanner); WTF_MAKE_FAST_ALLOCATED(HTMLPreloadScanner);
 public:
     static PassOwnPtr<HTMLPreloadScanner> create(const HTMLParserOptions& options, const KURL& documentURL, PassOwnPtr<CachedDocumentParameters> documentParameters)
     {
         return adoptPtr(new HTMLPreloadScanner(options, documentURL, documentParameters));
     }
 
 
     HTMLPreloadScanner(const HTMLParserOptions&, const KURL& documentURL, PassOwnPtr<CachedDocumentParameters>);
     ~HTMLPreloadScanner();
 
     void appendToEnd(const SegmentedString&);
     void scan(ResourcePreloader*, const KURL& documentBaseElementURL);
 
 private:
     TokenPreloadScanner m_scanner;
     SegmentedString m_source;
     HTMLToken m_token;
     OwnPtr<HTMLTokenizer> m_tokenizer;
 };
 
 }
 
 #endif