Have HashMap<KeyType, AtomicString>::get() return a const reference

Source/core/html/forms/FormController.cpp

 /*
  * Copyright (C) 2006, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010, 2011, 2012 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 276 matching lines @@
 }
 
 // ----------------------------------------------------------------------------
 
 class FormKeyGenerator {
     WTF_MAKE_NONCOPYABLE(FormKeyGenerator);
     WTF_MAKE_FAST_ALLOCATED;
 
 public:
     static PassOwnPtr<FormKeyGenerator> create() { return adoptPtr(new FormKeyGenerator); }
-    AtomicString formKey(const HTMLFormControlElementWithState&);
+    const AtomicString& formKey(const HTMLFormControlElementWithState&);
     void willDeleteForm(HTMLFormElement*);
 
 private:
     FormKeyGenerator() { }
 
     typedef HashMap<HTMLFormElement*, AtomicString> FormToKeyMap;
     typedef HashMap<String, unsigned> FormSignatureToNextIndexMap;
     FormToKeyMap m_formToKeyMap;
     FormSignatureToNextIndexMap m_formSignatureToNextIndexMap;
 };
@@ skipping 27 matching lines @@
     // as a session key.
     actionURL.setQuery(String());
     StringBuilder builder;
     if (!actionURL.isEmpty())
         builder.append(actionURL.string());
 
     recordFormStructure(form, builder);
     return builder.toString();
 }
 
-AtomicString FormKeyGenerator::formKey(const HTMLFormControlElementWithState& control)
+const AtomicString& FormKeyGenerator::formKey(const HTMLFormControlElementWithState& control)
 {
     HTMLFormElement* form = ownerFormForState(control);
     if (!form) {
-        DEFINE_STATIC_LOCAL(AtomicString, formKeyForNoOwner, ("No owner", AtomicString::ConstructFromLiteral));
+        DEFINE_STATIC_LOCAL(const AtomicString, formKeyForNoOwner, ("No owner", AtomicString::ConstructFromLiteral));
         return formKeyForNoOwner;
     }
     FormToKeyMap::const_iterator it = m_formToKeyMap.find(form);
     if (it != m_formToKeyMap.end())
         return it->value;
 
     String signature = formSignature(*form);
     ASSERT(!signature.isNull());
     FormSignatureToNextIndexMap::AddResult result = m_formSignatureToNextIndexMap.add(signature, 0);
     unsigned nextIndex = result.iterator->value++;
 
-    StringBuilder builder;
-    builder.append(signature);
-    builder.appendLiteral(" #");
-    builder.appendNumber(nextIndex);
-    AtomicString formKey = builder.toAtomicString();
-    m_formToKeyMap.add(form, formKey);
-    return formKey;
+    StringBuilder formKeyBuilder;
+    formKeyBuilder.append(signature);
+    formKeyBuilder.appendLiteral(" #");
+    formKeyBuilder.appendNumber(nextIndex);
+    FormToKeyMap::AddResult addFormKeyresult = m_formToKeyMap.add(form, formKeyBuilder.toAtomicString());
+    return addFormKeyresult.iterator->value;
 }
 
 void FormKeyGenerator::willDeleteForm(HTMLFormElement* form)
 {
     ASSERT(form);
     m_formToKeyMap.remove(form);
 }
 
 // ----------------------------------------------------------------------------
 
@@ skipping 141 matching lines @@
     m_formElementsWithState.add(control);
 }
 
 void FormController::unregisterFormElementWithState(HTMLFormControlElementWithState* control)
 {
     RELEASE_ASSERT(m_formElementsWithState.contains(control));
     m_formElementsWithState.remove(control);
 }
 
 } // namespace WebCore