Add a comma delimited syntax parser and use it for Accept-CH

Source/platform/network/HTTPParsers.cpp

 /*
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple 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:
@@ skipping 26 matching lines @@
 #include "wtf/MathExtras.h"
 #include "wtf/text/CString.h"
 #include "wtf/text/StringBuilder.h"
 #include "wtf/text/WTFString.h"
 #include "wtf/unicode/CharacterNames.h"
 
 using namespace WTF;
 
 namespace blink {
 
+static bool isWhitespace(UChar chr)
+{
+    return (chr == ' ') || (chr == '\t');
+}
+
 // true if there is more to parse, after incrementing pos past whitespace.
 // Note: Might return pos == str.length()
 static inline bool skipWhiteSpace(const String& str, unsigned& pos, bool fromHttpEquivMeta)
 {
     unsigned len = str.length();
 
     if (fromHttpEquivMeta) {
         while (pos < len && str[pos] <= ' ')
             ++pos;
     } else {
-        while (pos < len && (str[pos] == '\t' || str[pos] == ' '))
+        while (pos < len && isWhitespace(str[pos]))
             ++pos;
     }
 
     return pos < len;
 }
 
 // Returns true if the function can match the whole token (case insensitive)
 // incrementing pos on match, otherwise leaving pos unchanged.
 // Note: Might return pos == str.length()
 static inline bool skipToken(const String& str, unsigned& pos, const char* token)
@@ skipping 776 matching lines @@
 
     if (!cacheControlHeader.containsNoCache) {
         // Handle Pragma: no-cache
         // This is deprecated and equivalent to Cache-control: no-cache
         // Don't bother tokenizing the value, it is not important
         cacheControlHeader.containsNoCache = pragmaValue.lower().contains(noCacheDirective);
     }
     return cacheControlHeader;
 }
 
+void parseCommaDelimitedHeader(const String& headerValue, CommaDelimitedHeaderSet& headerSet)
+{
+    Vector<String> results;
+    headerValue.split(",", results);
+    for (auto& value : results)
+        headerSet.add(value.stripWhiteSpace(isWhitespace));
 }
+
+}