HTTPHeaderMap: Favor composition over inheritance.

Source/platform/network/HTTPHeaderMap.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2009 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 23 matching lines @@
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/AtomicStringHash.h"
 #include "wtf/text/StringHash.h"
 #include <utility>
 
 namespace blink {
 
 typedef Vector<std::pair<String, String> > CrossThreadHTTPHeaderMapData;
 
 // FIXME: Not every header fits into a map. Notably, multiple Set-Cookie header fields are needed to set multiple cookies.
-class PLATFORM_EXPORT HTTPHeaderMap : public HashMap<AtomicString, AtomicString, CaseFoldingHash> {
+class PLATFORM_EXPORT HTTPHeaderMap {
 public:
     HTTPHeaderMap();
     ~HTTPHeaderMap();
 
     // Gets a copy of the data suitable for passing to another thread.
     PassOwnPtr<CrossThreadHTTPHeaderMapData> copyData() const;
 
     void adopt(PassOwnPtr<CrossThreadHTTPHeaderMapData>);
 
-    const AtomicString& get(const AtomicString& name) const;
+    typedef HashMap<AtomicString, AtomicString, CaseFoldingHash> MapType;
+    typedef MapType::AddResult AddResult;
+    typedef MapType::const_iterator const_iterator;
 
-    AddResult add(const AtomicString& name, const AtomicString& value);
+    size_t size() const { return m_headers.size(); }
+    const_iterator begin() const { return m_headers.begin(); }
+    const_iterator end() const { return m_headers.end(); }
+    const_iterator find(const AtomicString &k) const { return m_headers.find(k); }
+    void clear() { m_headers.clear(); }
+    const AtomicString& get(const AtomicString& k) const { return m_headers.get(k); }
+    AddResult set(const AtomicString& k, const AtomicString& v) { return m_headers.set(k, v); }
+    AddResult add(const AtomicString& k, const AtomicString& v) { return m_headers.add(k, v); }
+    void remove(const AtomicString& k) { m_headers.remove(k); }
+    bool operator!=(const HTTPHeaderMap &rhs) const { return m_headers != rhs.m_headers; }
 
     // Alternate accessors that are faster than converting the char* to AtomicString first.
     bool contains(const char*) const;
     const AtomicString& get(const char*) const;
     AddResult add(const char* name, const AtomicString& value);
 
+private:
+    HashMap<AtomicString, AtomicString, CaseFoldingHash> m_headers;
 };
 
 } // namespace blink
 
 #endif // HTTPHeaderMap_h