Don't convert HEAD requests to GETs on 303 redirects.

net/url_request/url_request.cc

 // Copyright (c) 2011 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.
 
 #include "net/url_request/url_request.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
@@ skipping 677 matching lines @@
   }
 
   if (!location.is_valid())
     return ERR_INVALID_URL;
 
   if (!job_->IsSafeRedirect(location)) {
     DVLOG(1) << "disallowing redirect: unsafe protocol";
     return ERR_UNSAFE_REDIRECT;
   }
 
-  // For 303 redirects, all request methods are converted to GETs, as per RFC
-  // 2616.  The latest httpbis draft also allows POST requests to be converted
-  // to GETs when following 301/302 redirects for historical reasons.  Most
-  // major browsers do this and so shall we.  The RFC says to prompt the user
-  // to confirm the generation of new requests, other than GET and HEAD
-  // requests, but IE omits these prompts and so shall we.
-  // See:  http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p2-semantics-latest.html#status.3xx
+  // For 303 redirects, all request methods except HEAD are converted to GET,
+  // as per the latest httpbis draft.  The draft also allows POST requests to
+  // be converted to GETs when following 301/302 redirects, for historical
+  // reasons. Most major browsers do this and so shall we.  Both RFC 2616 and
+  // the httpbis draft say to prompt the user to confirm the generation of new
+  // requests, other than GET and HEAD requests, but IE omits these prompts and
+  // so shall we.
+  // See:  https://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-17#section-7.3
   bool was_post = method_ == "POST";
-  if (http_status_code == 303 ||
+  if ((http_status_code == 303 && method_ != "HEAD") ||
       ((http_status_code == 301 || http_status_code == 302) && was_post)) {
     method_ = "GET";
     upload_ = NULL;
     if (was_post) {
       // If being switched from POST to GET, must remove headers that were
       // specific to the POST and don't have meaning in GET. For example
       // the inclusion of a multipart Content-Type header in GET can cause
       // problems with some servers:
       // http://code.google.com/p/chromium/issues/detail?id=843
       StripPostSpecificHeaders(&extra_request_headers_);
@@ skipping 171 matching lines @@
 
 void URLRequest::SetUnblockedOnDelegate() {
   if (!blocked_on_delegate_)
     return;
   blocked_on_delegate_ = false;
   load_state_param_.clear();
   net_log_.EndEvent(NetLog::TYPE_URL_REQUEST_BLOCKED_ON_DELEGATE, NULL);
 }
 
 }  // namespace net