Apply user agent exactly once for requests from Blink.

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 230 matching lines @@
 
   // The remaining modifications are only necessary for HTTP and HTTPS.
   if (!request.url().isEmpty() && !request.url().protocolIsInHTTPFamily())
     return;
 
   if (frame()->loader().loadType() == FrameLoadTypeReload)
     request.clearHTTPHeaderField("Save-Data");
 
   if (frame()->settings() && frame()->settings()->dataSaverEnabled())
     request.setHTTPHeaderField("Save-Data", "on");
-
-  frame()->loader().applyUserAgent(request);
 }
 
 CachePolicy FrameFetchContext::getCachePolicy() const {
   if (m_document && m_document->loadEventFinished())
     return CachePolicyVerify;
 
   FrameLoadType loadType = frame()->loader().loadType();
   if (loadType == FrameLoadTypeReloadBypassingCache)
     return CachePolicyReload;
 
@@ skipping 750 matching lines @@
                                                     response);
 }
 
 DEFINE_TRACE(FrameFetchContext) {
   visitor->trace(m_document);
   visitor->trace(m_documentLoader);
   FetchContext::trace(visitor);
 }
 
 }  // namespace blink