Send net's ReferrerPolicy back to Blink while following redirects

net/url_request/url_request.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_URL_REQUEST_URL_REQUEST_H_
 #define NET_URL_REQUEST_URL_REQUEST_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 65 matching lines @@
   // Callback function implemented by protocol handlers to create new jobs.
   // The factory may return NULL to indicate an error, which will cause other
   // factories to be queried.  If no factory handles the request, then the
   // default job will be used.
   typedef URLRequestJob* (ProtocolFactory)(URLRequest* request,
                                            NetworkDelegate* network_delegate,
                                            const std::string& scheme);
 
   // A ReferrerPolicy for the request can be set with
   // set_referrer_policy() and controls the contents of the Referer
-  // header when URLRequest follows server redirects.
+  // header when URLRequest follows server redirects. Note that setting
+  // a ReferrerPolicy on the request has no effect on the Referer header
+  // of the initial leg of the request; the caller is responsible for
+  // setting the initial Referer, and the ReferrerPolicy only controls
+  // what happens to the Referer while following redirects.
   enum ReferrerPolicy {
     // Clear the referrer header if the protocol changes from HTTPS to
     // HTTP. This is the default behavior of URLRequest.
     CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE,
     // A slight variant on
     // CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE: If the
     // request downgrades from HTTPS to HTTP, the referrer will be
     // cleared. If the request transitions cross-origin (but does not
     // downgrade), the referrer's granularity will be reduced (currently
     // stripped down to an origin rather than a full URL). Same-origin
@@ skipping 756 matching lines @@
 
   // The raw header size of the response.
   int raw_header_size_;
 
   DISALLOW_COPY_AND_ASSIGN(URLRequest);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_H_