Reduce allocation size of FormData::m_entries.

Source/core/html/FormData.h

 /*
  * 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:
  *
  *     * 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 62 matching lines @@
     void set(const String& name, const String& value);
     void set(const String& name, Blob*, const String& filename = String());
 
     // Internal functions.
 
     void makeOpaque() { m_opaque = true; }
     bool opaque() const { return m_opaque; }
 
     const WTF::TextEncoding& encoding() const { return m_encoding; }
     class Entry;
-    const HeapVector<Entry>& entries() const { return m_entries; }
+    const HeapVector<Member<const Entry>>& entries() const { return m_entries; }
     size_t size() const { return m_entries.size(); }
     // TODO(tkent): Rename appendFoo functions to |append| for consistency with
     // public function.
     void appendData(const String& key, const String& value);
     void appendData(const String& key, int value);
     void appendBlob(const String& key, Blob*, const String& filename = String());
     String decode(const CString& data) const;
 
     PassRefPtr<EncodedFormData> encodeFormData(EncodedFormData::EncodingType = EncodedFormData::FormURLEncoded);
     PassRefPtr<EncodedFormData> encodeMultiPartFormData();
 
 private:
     explicit FormData(const WTF::TextEncoding&);
     explicit FormData(HTMLFormElement*);
-    void setEntry(const Entry&);
+    void setEntry(const Entry*);
     CString encodeAndNormalize(const String& key) const;
     IterationSource* startIteration(ScriptState*, ExceptionState&) override;
 
     WTF::TextEncoding m_encoding;
-    HeapVector<Entry> m_entries;
+    // Entry pointers in m_entries never be nullptr.
+    HeapVector<Member<const Entry>> m_entries;
     bool m_opaque;
 };
 
 // Represents entry, which is a pair of a name and a value.
 // https://xhr.spec.whatwg.org/#concept-formdata-entry
-class FormData::Entry {
-    ALLOW_ONLY_INLINE_ALLOCATION();
+// Entry objects are immutable.
+class FormData::Entry : public GarbageCollectedFinalized<FormData::Entry> {
 public:
     Entry(const CString& key, const CString& data) : m_key(key), m_data(data) { }
     Entry(const CString& key, Blob* blob, const String& filename) : m_key(key), m_blob(blob), m_filename(filename) { }
     DECLARE_TRACE();
 
     bool isString() const { return !m_blob; }
     bool isFile() const { return m_blob; }
     const CString& key() const { return m_key; }
     const CString& data() const { return m_data; }
     Blob* blob() const { return m_blob.get(); }
     File* file() const;
     const String& filename() const { return m_filename; }
 
 private:
-    CString m_key;
-    CString m_data;
-    Member<Blob> m_blob;
-    String m_filename;
+    const CString m_key;
+    const CString m_data;
+    const Member<Blob> m_blob;
+    const String m_filename;
 };
 
 } // namespace blink
 
-WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS(blink::FormData::Entry);
-
 #endif // FormData_h