Update HTTPHeaderMap wrappers to use AtomicString type for header values

Source/platform/network/HTTPRequest.h

 /*
  * Copyright (C) 2010 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 40 matching lines @@
 
     String requestMethod() const { return m_requestMethod; }
     void setRequestMethod(const String& method) { m_requestMethod = method; }
 
     KURL url() const { return m_url; }
     void setURL(const KURL& url) { m_url = url; }
 
     const Vector<unsigned char>& body() const { return m_body; }
 
     const HTTPHeaderMap& headerFields() const { return m_headerFields; }
-    void addHeaderField(const AtomicString& name, const String& value) { m_headerFields.add(name, value); }
-    void addHeaderField(const char* name, const String& value) { m_headerFields.add(name, value); }
+    void addHeaderField(const AtomicString& name, const AtomicString& value) { m_headerFields.add(name, value); }
+    void addHeaderField(const char* name, const AtomicString& value) { m_headerFields.add(name, value); }
 
 protected:
     HTTPRequest();
     HTTPRequest(const String& requestMethod, const KURL&, HTTPVersion);
 
     // Parsing helpers.
     size_t parseRequestLine(const char* data, size_t length, String& failureReason);
     size_t parseHeaders(const char* data, size_t length, String& failureReason);
     size_t parseRequestBody(const char* data, size_t length);
 
     KURL m_url;
     HTTPVersion m_httpVersion;
     String m_requestMethod;
     HTTPHeaderMap m_headerFields;
     Vector<unsigned char> m_body;
 };
 
 } // namespace WebCore
 
 #endif // HTTPRequest_h