Literal AtomicString construction can rely on strlen optimization.

third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp

 /*
  *  Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005-2007 Alexey Proskuryakov <ap@webkit.org>
  *  Copyright (C) 2007, 2008 Julien Chaffraix <jchaffraix@webkit.org>
  *  Copyright (C) 2008, 2011 Google Inc. All rights reserved.
  *  Copyright (C) 2012 Intel Corporation
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
@@ skipping 765 matching lines @@
 
     if (!initSend(exceptionState))
         return;
 
     RefPtr<EncodedFormData> httpBody;
 
     if (areMethodAndURLValidForSend()) {
         httpBody = body->encodeMultiPartFormData();
 
         if (getRequestHeader(HTTPNames::Content_Type).isEmpty()) {
-            AtomicString contentType = AtomicString("multipart/form-data; boundary=", AtomicString::ConstructFromLiteral) + httpBody->boundary().data();
+            AtomicString contentType = AtomicString("multipart/form-data; boundary=") + httpBody->boundary().data();
             setRequestHeaderInternal(HTTPNames::Content_Type, contentType);
         }
     }
 
     createRequest(httpBody.release(), exceptionState);
 }
 
 void XMLHttpRequest::send(DOMArrayBuffer* body, ExceptionState& exceptionState)
 {
     WTF_LOG(Network, "XMLHttpRequest %p send() ArrayBuffer %p", this, body);
@@ skipping 484 matching lines @@
 }
 
 AtomicString XMLHttpRequest::finalResponseMIMETypeWithFallback() const
 {
     AtomicString finalType = finalResponseMIMEType();
     if (!finalType.isEmpty())
         return finalType;
 
     // FIXME: This fallback is not specified in the final MIME type algorithm
     // of the XHR spec. Move this to more appropriate place.
-    return AtomicString("text/xml", AtomicString::ConstructFromLiteral);
+    return AtomicString("text/xml");
 }
 
 bool XMLHttpRequest::responseIsXML() const
 {
     return DOMImplementation::isXMLMIMEType(finalResponseMIMETypeWithFallback());
 }
 
 bool XMLHttpRequest::responseIsHTML() const
 {
     return equalIgnoringCase(finalResponseMIMEType(), "text/html");
@@ skipping 401 matching lines @@
     visitor->trace(m_responseDocumentParser);
     visitor->trace(m_progressEventThrottle);
     visitor->trace(m_upload);
     visitor->trace(m_blobLoader);
     XMLHttpRequestEventTarget::trace(visitor);
     DocumentParserClient::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink