save-data header value gets appended on page refreshes

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

 /*
  * Copyright (C) 2013 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 102 matching lines @@
     }
 
     if (m_document)
         request.setExternalRequestStateFromRequestorAddressSpace(m_document->addressSpace());
 
     // The remaining modifications are only necessary for HTTP and HTTPS.
     if (!request.url().isEmpty() && !request.url().protocolIsInHTTPFamily())
         return;
 
     if (frame()->settings() && frame()->settings()->dataSaverEnabled())
-        request.addHTTPHeaderField("Save-Data", "on");
+        request.setHTTPHeaderField("Save-Data", "on");
 
     frame()->loader().applyUserAgent(request);
 }
 
 void FrameFetchContext::setFirstPartyForCookies(ResourceRequest& request)
 {
     if (frame()->tree().top()->isLocalFrame())
         request.setFirstPartyForCookies(toLocalFrame(frame()->tree().top())->document()->firstPartyForCookies());
 }
 
@@ skipping 673 matching lines @@
 }
 
 DEFINE_TRACE(FrameFetchContext)
 {
     visitor->trace(m_document);
     visitor->trace(m_documentLoader);
     FetchContext::trace(visitor);
 }
 
 } // namespace blink