Update HTTPHeaderMap wrappers to use AtomicString type for header values

Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 544 matching lines @@
     if (updateBackForwardList == UpdateBackForwardList || sameDocumentNavigationSource == SameDocumentNavigationPushState)
         navigationHistoryPolicy = NavigationCreatedHistoryEntry;
     m_client->dispatchDidNavigateWithinPage(navigationHistoryPolicy);
     m_client->dispatchDidReceiveTitle(m_frame->document()->title());
 
     if (m_currentItem) {
         m_currentItem->setURL(newURL);
         if (sameDocumentNavigationSource != SameDocumentNavigationDefault) {
             m_currentItem->setStateObject(data);
             m_currentItem->setFormData(0);
-            m_currentItem->setFormContentType(String());
+            m_currentItem->setFormContentType(nullAtom);
         }
     }
 
     if (m_frame->document()->loadEventFinished())
         m_client->postProgressFinishedNotification();
 }
 
 void FrameLoader::loadInSameDocument(const KURL& url, PassRefPtr<SerializedScriptValue> stateObject, bool isNewNavigation, ClientRedirectPolicy clientRedirect)
 {
     // If we have a state object, we cannot also be a new navigation.
@@ skipping 590 matching lines @@
         else if (m_loadType == FrameLoadTypeReloadFromOrigin) {
             request.setHTTPHeaderField("Cache-Control", "no-cache");
             request.setHTTPHeaderField("Pragma", "no-cache");
         }
     }
 
     if (isMainResource)
         request.setHTTPAccept(defaultAcceptHeader);
 
     // Make sure we send the Origin header.
-    addHTTPOriginIfNeeded(request, String());
+    addHTTPOriginIfNeeded(request, nullAtom);
 }
 
-void FrameLoader::addHTTPOriginIfNeeded(ResourceRequest& request, const String& origin)
+void FrameLoader::addHTTPOriginIfNeeded(ResourceRequest& request, const AtomicString& origin)
 {
     if (!request.httpOrigin().isEmpty())
         return;  // Request already has an Origin header.
 
     // Don't send an Origin header for GET or HEAD to avoid privacy issues.
     // For example, if an intranet page has a hyperlink to an external web
     // site, we don't want to include the Origin of the request because it
     // will leak the internal host name. Similar privacy concerns have lead
     // to the widespread suppression of the Referer header at the network
     // layer.
@@ skipping 345 matching lines @@
 {
     SandboxFlags flags = m_forcedSandboxFlags;
     if (Frame* parentFrame = m_frame->tree().parent())
         flags |= parentFrame->document()->sandboxFlags();
     if (HTMLFrameOwnerElement* ownerElement = m_frame->ownerElement())
         flags |= ownerElement->sandboxFlags();
     return flags;
 }
 
 } // namespace WebCore